What Are the COMLEX-USA Exams?

COMLEX-USA is the three-level medical licensing examination series for osteopathic physicians (DOs) in the United States. Administered by the National Board of Osteopathic Medical Examiners (NBOME), it assesses your ability to apply medical knowledge, clinical skills, and osteopathic principles to patient care.

If you attend an osteopathic medical school, you’ll need to pass Level 1 and Level 2-CE before graduating with your DO degree. You’ll take Level 3 after graduation, usually during residency, to demonstrate that you’re ready to care for patients independently. Passing all three levels checks off the exam requirement for licensure, though you’ll also need to meet your state medical board’s other requirements.

Your COMLEX-USA results can also play a role in your residency application, alongside your clinical performance, recommendation letters, and interviews. Below, I’ll walk you through what to expect at each level, how scoring works, and how to prepare.

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COMLEX Examination Series

The three COMLEX-USA levels assess your readiness for increasing responsibility in patient care:

• Level 1: Applying foundational biomedical sciences and osteopathic principles to clinical problems.
• Level 2-CE (Cognitive Evaluation): Applying clinical knowledge and osteopathic principles to patient care under supervision.
• Level 3: Making clinical decisions and managing patients in unsupervised osteopathic medical practice.

Testing times exclude breaks and other appointment activities. Confirm your school’s scheduling requirements before choosing a test date.

Taking Level 3 in 2027? Beginning January 13, the exam changes to four two-hour testing sessions in a single day. It will continue to include both multiple-choice questions and clinical decision-making (CDM) cases. Each case includes two to four questions using extended multiple-choice or short-answer formats.

COMLEX Eligibility Requirements

You’ll need to meet different requirements for each COMLEX-USA level, including completing the necessary education and having your academic and professional standing verified. You must also pass each level before taking the next.

Here’s how NBOME’s eligibility requirements break down.

Level 1 Eligibility

To take Level 1, you must:

• Complete your first year of study at an accredited college of osteopathic medicine.
• Have your dean attest that you’re in good academic and professional standing.

Being eligible doesn’t necessarily mean it’s time to test. Students typically take Level 1 near the end of their second year, and your school may have additional requirements before approving you to sit for the exam.

Level 2-CE Eligibility

To take Level 2-CE, you must:

• Pass COMLEX-USA Level 1.
• Complete your second year at an accredited college of osteopathic medicine.
• Have your dean attest that you’re in good academic and professional standing.

Your school will help you plan your exam around clinical rotations, graduation requirements, and residency application deadlines.

Level 3 Eligibility

To take Level 3, you generally must:

• Pass COMLEX-USA Levels 1 and 2-CE.
• Graduate from an accredited college of osteopathic medicine with a DO degree.
• Have your residency program director attest that you’re in good academic and professional standing.
• Meet NBOME’s clinical skills verification requirement.

For graduates in the Classes of 2026–2028, clinical skills verification is provided through an attestation from their medical school dean. Beginning with the Class of 2029, NBOME will offer two pathways: the Core Competency Capstone for DOs (C3DO) and Comprehensive Competency Verification (CCV).

NBOME recommends completing at least six months of residency before taking Level 3. This is a recommendation for most candidates, rather than a universal eligibility requirement.

If you aren’t enrolled in a residency program, NBOME offers a petition process for an alternate eligibility pathway, reviewed case by case. I recommend checking with your school or residency coordinator before scheduling so you have time to complete the required approvals.

How Is COMLEX Scored?

COMLEX-USA Level 1 is reported as pass/fail. Level 2-CE and Level 3 receive three-digit scores.

According to NBOME’s scoring guidance, your results are converted into a standardized score to account for differences between exam forms. That score isn’t your percentage correct or your percentile. Any unscored pretest questions included in your exam won’t count toward your result.

Although Level 1 doesn’t give you a numerical score, you’ll still get feedback through your Formative Performance Profile. It shows how you performed overall and in individual content areas compared with first-time test-takers who passed. This can help you see where you’re doing well and which areas could use more attention.

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How Hard is COMLEX?

COMLEX is a challenging exam series, but most first-time test-takers pass each level. You’ll

need to do more than recall facts: the exams ask you to apply medical knowledge and osteopathic principles to patient scenarios, often while working through lengthy questions under time pressure.

For context, NBOME’s 2025 annual report reports these first-time pass rates:

These rates are reassuring, but they aren’t a prediction of your individual result. They also reflect candidates at different stages of training, so Level 3’s higher pass rate doesn’t necessarily mean it’s the easiest exam.

COMLEX Study Tips

Start with a realistic study schedule that includes content review, practice questions, and time to revisit topics you find challenging. Work backward from your exam date, keeping classes, rotations, and other commitments in mind. Our COMLEX Level 1 study guide can help you get started.

Here are a few strategies I recommend:

• • Build on what you’re learning in school. Review material throughout your courses and rotations so your dedicated study time feels more like review than starting from scratch.
  • Use practice questions to guide your review. Read the explanations for questions you miss—and those you guessed correctly. Figure out whether you missed a concept, misread the question, or struggled with timing, then adjust your studying accordingly.
  • Make room for osteopathic principles and OMT. Include regular review of osteopathic manipulative treatment and its clinical applications rather than leaving it all for the final week.
  • Use NBOME’s practice resources. Try the official sample questions and tutorials to get familiar with the exam format. COMSAE self-assessments can help you identify knowledge gaps, but they don’t guarantee a particular COMLEX result.
  • Practice pacing and exam-specific tasks. Include timed question blocks in your preparation. For Level 3, work through NBOME’s clinical decision-making tutorial so you understand how to answer the cases.
  • Plan for breaks and sleep. Give yourself a schedule you can sustain, with room to rest and recharge. If you fall behind, reassess your priorities rather than trying to make up every missed hour at once.

Related: How to Use COMSAEs to Excel on COMLEX: Study Tips & FAQs 

USMLE vs. COMLEX

USMLE and COMLEX-USA are both medical licensing exam series. The main difference is that MD students take USMLE, while DO students must take COMLEX-USA and can also choose to take USMLE.

The exams cover many of the same medical sciences and patient-care concepts. However, COMLEX-USA also integrates osteopathic principles and osteopathic manipulative treatment (OMT).

If you attend an osteopathic medical school, taking USMLE does not replace your COMLEX-USA requirements. Whether taking both makes sense depends on your target residency programs, their exam policies, and the extra preparation time and cost involved. I recommend reviewing those policies with your school’s residency advisor before deciding.

For a closer look, see our USMLE Step 1 vs. COMLEX Level 1 comparison.

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