L.E.K. Case Interview: Candidate-Led Format, Written Case, and Prep Strategy (2026)

L.E.K. Consulting uses a candidate-led case interview format across two rounds, with cases concentrated in life sciences, private equity due diligence, healthcare services, and industrials. Round 1 includes 2–3 interviews with quantitative and strategic case types; Round 2 adds 2–3 additional interviews plus a 60-minute written case where candidates analyze a 40–50 page slide packet and present findings. Most offices require a numerical reasoning pre-screen before Round 1 — a 30-minute GMAT-style test with 30+ multiple-choice questions that functions as an eliminatory gate. Founded in London in 1983, L.E.K. operates approximately 26 offices globally and sits in the Tier 2 strategy consulting tier alongside Oliver Wyman, Roland Berger, and Kearney.

What L.E.K. Is (and Why It Interviews Differently)

L.E.K. Consulting was founded in 1983 in London — the initials stand for co-founders James Lawrence, Iain Evans, and Richard Koch. Today it operates about 26 offices globally with roughly 1,600 consultants. It sits comfortably in the Tier 2 strategy consulting tier alongside Oliver Wyman, Roland Berger, and Kearney — consistently placed above Big 4 consulting in prestige rankings, below MBB.

What sets L.E.K. apart operationally is where its revenue comes from. Unlike McKinsey or BCG, which spread work broadly across industries, L.E.K. has built genuine depth in life sciences (biopharma, MedTech, CRO), private equity commercial due diligence, consumer, and industrials. According to L.E.K.'s official interview preparation page, candidates should "hone your skills in the areas most relevant to L.E.K.'s core sectors" — which is as close to a direct signal as a firm will give you.

That industry mix shows up directly in the cases you'll receive. A candidate preparing only on general business cases is under-prepared for L.E.K. by default.

The Full L.E.K. Interview Process

Stage 0: Application and Numerical Pre-Screen

After CV review and a brief screening call, most L.E.K. offices send a numerical reasoning test before any interviews. The format is typically a 30-minute Zoom session with 30+ multiple-choice questions — GMAT-style quantitative reasoning covering data interpretation, percentage calculations, rate problems, and basic financial math.

Candidates on Glassdoor describe the numerical test as fast-paced and elimination-level: "you need to be quick and accurate, not just conceptually correct." The pass threshold is not published, but candidate accounts suggest it's meaningfully selective.

Preparation implication: Don't treat the numerical test as a warmup for case prep. It's a gate. Budget 2-3 weeks of dedicated quant practice (GMAT Problem Solving + Data Sufficiency sections work well) before your test date.

Stage 1: Round 1 — Two Case Interviews

Round 1 at most offices consists of 2–3 interviews of 30–45 minutes each. Every interview includes a short behavioral/fit section (5–10 minutes) followed by a full case.

The two case types candidates report encountering:

Both cases are fully candidate-led. You set the direction. You request the data. You propose the next analytical step. If you've prepared primarily with McKinsey-style interviewer-led practice, you'll feel the difference immediately — no guiding question sequence, no structured hand-offs. You either drive or you stall.

According to multiple candidate reports on PrepLounge, the quantitative case often involves "pushing real numbers at you mid-case" rather than abstracting to percentages. Clean, fast arithmetic matters more than it does at firms where cases stay at the conceptual level.

Stage 2: Round 2 — Cases Plus Written Case

Round 2 is longer and more taxing: typically 2–3 full case interviews with senior interviewers (managers, principals, or partners), followed by a 60-minute written case. Total time can reach 4 hours.

The written case structure:

1. You receive a packet of 40–50 slides containing data exhibits, financial summaries, market context, and client background
2. You have 60 minutes to analyze the packet, identify the key question, and build a concise output — typically 8–10 slides
3. You present your findings to the interviewer, who probes your reasoning and challenges your conclusions

If you've never practiced building structured slide recommendations under a strict time limit, the written case is where strong verbal case performers often stumble. For a complete breakdown of the written case format and slide structure, see our written case interview guide.

How L.E.K. Cases Differ From MBB

This is the comparison that matters most for candidates who've spent weeks preparing for McKinsey, BCG, or Bain.

The practical implication for your prep: L.E.K. rewards candidates who build clean structures and execute data-heavy analysis quickly. Strong frameworks with slow or imprecise math won't clear Round 1. Build your quantitative speed first, then your framework quality.

For general framework fundamentals that apply across all candidate-led formats, start with our complete case interview frameworks guide.

L.E.K.'s Sector Focus: What It Means for Case Prep

L.E.K. publishes its sector focus openly: life sciences, healthcare services, private equity, consumer, and industrials. "If you have a background in this area," the careers page reads, "it is ideal if you prepare for cases focusing on biopharma, healthcare and related services, and MedTech."

For candidates without those backgrounds, there's a vocabulary gap to close before any case technique matters.

Life Sciences and Healthcare Cases

Life sciences cases at L.E.K. typically involve one of these scenarios:

• Drug market sizing: Estimate revenue potential for a new therapeutic entering a defined indication
• CRO (contract research organization) strategy: A CRO considering service expansion or geographic entry
• MedTech entry: A medical device company evaluating a new market or evaluating an acquisition
• Biopharma profitability: Declining margins at a specialty pharma company despite revenue growth
• AI in drug discovery: A technology company assessing commercialization options for a compound-identification platform

According to Wall Street Oasis interview reports, candidates have encountered prompts including "strategy for biopharma," "business opportunity for diagnostic company," and "open-ended evaluation of a biopharma company." The framework mechanics are identical to standard case frameworks — the challenge is the vocabulary.

Terms to know before your interview: payer mix (how a drug's revenue splits between insurance types), formulary inclusion (whether a drug is covered under an insurer's approved drug list), reimbursement rates (what payers actually pay per prescription), patent cliff (revenue loss when a drug's patent expires and generics enter), Phase II/III/IV (clinical trial stages and their cost/risk profiles), and CRO (a company that runs clinical trials on behalf of pharma clients).

Private Equity Due Diligence Cases

L.E.K. is one of the top global firms for PE commercial due diligence. Cases in this space look like:

• "A PE fund is considering acquiring Company X at a 9x EBITDA multiple. Should they proceed?"
• "Assess the market size and growth trajectory for this B2B healthcare software sector"
• "What is the competitive position of this target versus its three nearest rivals, and is it defensible?"

The framework for PE due diligence cases sits between market entry and profitability — you're assessing market attractiveness, then evaluating whether this specific company can win and sustain its position. Our market entry framework guide covers the attractiveness assessment piece in depth.

Worked Example 1: L.E.K. Life Sciences Profitability Case

Prompt: "A specialty pharma company has seen EBITDA margin decline from 28% to 13% over three years, despite revenue growing from $400M to $560M. What's driving this, and what should they do?"

Step 1 — Quantify the problem before diagnosing it:

• Year 1: Revenue $400M × 28% margin = $112M EBITDA; Cost base = $288M
• Year 3: Revenue $560M × 13% margin = $72.8M EBITDA; Cost base = $487.2M

Cost growth: $487.2M – $288M = $199.2M increase to generate only $160M in additional revenue. The company spent $1.25 for every $1.00 of revenue growth. That's the core problem.

Step 2 — Structure the cost analysis:

Break the cost base into: COGS (variable, tied to volume), SG&A (selling, general, admin — often semi-fixed), and R&D (investment in future pipeline).

Hypothesis: Excessive SG&A expansion — a scaled-up commercial organization that hasn't returned proportional revenue.

Step 3 — Interpret the data: (In a real L.E.K. case, you'd explicitly request this breakdown.)

Assume the interviewer provides: COGS held stable at 40% of revenue. SG&A grew from 20% to 31% of revenue. R&D from 12% to 16%.

• SG&A Year 1: $400M × 20% = $80M
• SG&A Year 3: $560M × 31% = $173.6M → growth of $93.6M

SG&A alone explains nearly half the EBITDA loss ($39.2M in absolute terms: $112M – $72.8M).

Recommendation: "The core issue is SG&A over-expansion — the company added $93.6M in selling costs while generating $160M in revenue growth. I'd recommend a SG&A efficiency audit focused on sales force productivity by territory, benchmarked against the pharma peer median of approximately 20-22% of revenue. The immediate lever is identifying which markets have the lowest revenue-per-sales-rep and restructuring or exiting those territories."

For structured recommendation practice, see our case interview synthesis guide.

Worked Example 2: L.E.K. PE Due Diligence Case

Prompt: "A PE fund is evaluating acquiring a mid-size CRO with $200M revenue, 17% EBITDA margins, priced at 10x EBITDA. Should they proceed? What are your key diligence questions?"

Structure — Two core questions:

1. Is the market attractive?

• Global CRO market is approximately $75-80B and growing at 7-8% annually, driven by pharma companies increasingly outsourcing clinical trial execution to reduce fixed costs
• Market is fragmented: the top 5 players (IQVIA, Covance, PPD, Syneos, PRA) hold roughly 50% share; the remaining 50% is split across hundreds of specialty firms
• Tailwinds: rising R&D spend, complexity of late-stage oncology/rare disease trials, and pressure on pharma margins driving outsourcing

2. Does this company win in that market?

Questions I'd ask:

• What is the CRO's therapeutic specialization? (Oncology CROs command premium margins vs. general Phase I-II shops)
• What is client concentration? If top 3 clients represent 50%+ of revenue, that's a major risk
• What is backlog? (A 12-18 month contracted backlog signals revenue visibility)
• Are contracts milestone-based or time-and-materials? (Milestone contracts create margin risk on overruns)

Quantify the deal:

• EBITDA = $200M × 17% = $34M
• Enterprise value at 10x = $340M
• At a conservative 7x exit multiple (down from 10x at entry, reflecting growth deceleration at maturity) after 5 years with 8% annual revenue growth: Revenue = $200M × (1.08)^5 ≈ $294M. EBITDA at 17% = ~$50M. Exit EV at 7x = $350M.

That's barely 3% total return over a 5-year hold (~0.6% annualized IRR) — not attractive unless margin expansion or multiple expansion is achievable. The case depends heavily on whether the CRO can expand margins through scale.

Recommendation: "I'd proceed with diligence only if the CRO has oncology or rare disease specialization and client concentration below 30% for its top client. The current deal math is tight — the return only works if the firm can expand margins from 17% to 20%+ through operational leverage. The first diligence step would be a revenue quality analysis: how much of the $200M is contracted vs. at-risk, and what is the backlog-to-revenue ratio?"

For broader market sizing methodology used in PE cases, see our market sizing guide.

Common Mistakes in L.E.K. Interviews

1. Treating it like a McKinsey interview L.E.K. is candidate-led. Sitting back and waiting for structure from the interviewer signals you haven't done your homework. Every practice case you run should be fully candidate-driven — you ask for the data, you propose the structure, you decide when to pivot.

2. Under-preparing the numerical pre-screen The numerical test is not a formality. Candidates who fail it don't get to the cases. Dedicate 2-3 weeks to GMAT-style quant practice before your test date, and time yourself strictly — the pacing matters as much as the accuracy.

3. Ignoring sector vocabulary Walking into a biopharma case and asking "what is formulary inclusion?" signals poor preparation. Spend 5-8 hours on L.E.K.'s core industries before your interviews. You don't need deep expertise — you need enough fluency that sector-specific prompts don't slow your thinking.

4. Over-reading the written case packet This is the most consistent failure pattern in Round 2. With 40-50 pages and 60 minutes, you are not supposed to read everything. Practice scanning: read the executive summary, identify the 2-3 financial exhibits that quantify the core problem, and skip supporting data unless your hypothesis requires it.

5. Hedging the synthesis Candidate reports on PrepLounge consistently cite unclear recommendations as a failure mode. A synthesis that says "it depends on several factors" without a clear directional recommendation reads as a fail, regardless of analytical quality. Practice giving a direct answer with structured support, even when the data is ambiguous. That's the skill being tested.

6. Insufficient mental math speed L.E.K. cases run faster than MBB cases in candidate accounts. If your mental math slows the case at key moments — mid-analysis, building toward a recommendation — it signals a fundamental skill gap. Use our mental math guide to build daily drills into your prep routine.

30-Day L.E.K. Prep Plan

For a full timeline that covers all consulting firms, see our consulting interview prep timeline. For candidates making a non-traditional transition into consulting, our career changer case interview guide covers how to position non-consulting experience effectively.

Bridge: Firm-Specific Guides

If you're evaluating multiple firms or want to understand how L.E.K.'s process compares to adjacent options:

• McKinsey: Interviewer-led format, no written case — see our McKinsey case interview guide for the PEI structure and problem-solving test prep
• BCG: Candidate-led with potential written case (Pymetrics online assessment replaced the older Potter test) — see our BCG case interview guide
• Oliver Wyman: Closest structural comparison to L.E.K. — candidate-led, quant-intensive, sector-specialist — see our Oliver Wyman case interview guide
• Written case format (firm-agnostic): Our written case interview guide covers BCG and Bain formats in depth; the L.E.K. format follows the same fundamentals

Test Your Knowledge

Practice Drills

Sources and Further Reading (checked March 14, 2026)

• L.E.K. official interview preparation resources: lek.com/join-lek/apply/interview-preparation
• L.E.K. market sizing interview guide (official video): lek.com/careers/lek-market-sizing-interview
• L.E.K. Consulting interview experiences (Glassdoor 2026): glassdoor.com/Interview/L-E-K-Consulting
• Management Consulted LEK case interview guide: managementconsulted.com/lek-case-interview
• Hacking the Case Interview — LEK case guide: hackingthecaseinterview.com/pages/lek-case-interview
• PrepLounge community — LEK Round 1 case format discussion: preplounge.com/consulting-forum/lek-first-round-cases
• Wall Street Oasis — LEK consulting interview questions (67 entries): wallstreetoasis.com/company/lek-consulting/interview