The Comprehensive Osteopathic Medical Licensing Examination (COMLEX-USA®) is the licensing exam sequence for osteopathic physicians (DOs) in the United States. Administered by the National Board of Osteopathic Medical Examiners (NBOME), COMLEX-USA® consists of three levels that must be passed for full medical licensure. This page focuses primarily on COMLEX-USA® Level 1 and Level 2-CE (Cognitive Evaluation), which are taken during medical school and are most relevant to current students. We cover the exam format, scoring, the relationship between COMLEX-USA® and the USMLE®, preparation strategies, and recommended resources.
COMLEX-USA Exam Sequence
The COMLEX-USA® series consists of three levels. Level 1 is taken during the preclinical years (typically after the second year of osteopathic medical school) and tests foundational biomedical science knowledge with an emphasis on osteopathic principles. Level 2-CE is taken during the clinical years and tests clinical knowledge, medical decision-making, and osteopathic patient management. Level 3 is taken during residency and assesses the ability to practice independently. All three levels must be passed for full DO licensure.
COMLEX-USA Level 1
Level 1 is a one-day, computer-based exam consisting of approximately 400 questions. The content covers the same foundational science disciplines as USMLE® Step 1 (anatomy, biochemistry, microbiology, pathology, pharmacology, physiology) but also includes osteopathic principles and practice (OPP), osteopathic manipulative treatment (OMT), and osteopathic philosophy. OPP/OMT content typically constitutes about 15 to 20 percent of the exam and includes questions about somatic dysfunction diagnosis, viscerosomatic reflexes, Chapman’s points, craniosacral mechanisms, and specific OMT techniques.
COMLEX-USA® Level 1 transitioned to pass/fail scoring in 2023, following the USMLE® Step 1 precedent. This means your result is reported as Pass or Fail with no numeric score. The same strategic implications apply: Level 2-CE has become the primary scored exam for residency applications from DO students.
COMLEX-USA Level 2-CE
Level 2-CE is a two-day, computer-based exam totaling approximately 800 questions. It covers the clinical disciplines (internal medicine, surgery, pediatrics, obstetrics and gynecology, psychiatry, family medicine, emergency medicine) with integrated OPP/OMT content throughout. Level 2-CE remains numerically scored and is now the primary standardized exam score in DO residency applications, mirroring the role that USMLE® Step 2 CK plays for MD applicants.
The scoring scale ranges approximately from 9 to 999, with 400 as the passing threshold and the national mean typically falling between 500 and 550. Competitive scores for most residency programs are generally in the 550 to 650 range, though expectations vary significantly by specialty and by program. Research your target programs to understand their score expectations, and use COMSAE practice exams to gauge your readiness relative to the passing standard.
Registration and Scheduling
Registration for COMLEX-USA® exams is managed through the NBOME website. Level 1 is typically taken at the end of the second year of osteopathic medical school, during a dedicated study block provided by most programs. Level 2-CE is taken during the clinical years, usually in the summer or fall of the third year, timed to have scores available for residency applications. The exam fee for Level 1 is approximately $660, and Level 2-CE is approximately $660 for Day 1 and $660 for Day 2 (total approximately $1,320). Exams are administered at Prometric testing centers throughout the United States. International testing locations are available for students completing international clinical rotations.
You may take each level up to four times within a defined period. If you do not pass after multiple attempts, additional educational requirements must be completed before reattempting. Most schools require passage of Level 1 before entering clinical rotations and passage of Level 2-CE before graduation.
COMLEX vs. USMLE: Should DO Students Take Both
A significant question for osteopathic medical students is whether to take both the COMLEX-USA® exams and the USMLE® exams. All DO students must take COMLEX-USA® for licensure. The USMLE® is optional for DO students but has historically been taken by those applying to ACGME-accredited (formerly allopathic) residency programs, because some programs were more familiar with USMLE® scores.
Since the merger of the AOA and ACGME residency systems (completed in 2020), all residency programs now accept DO applicants. Many programs have become more familiar with COMLEX-USA® scoring. However, some competitive programs, particularly in surgical subspecialties, may still prefer seeing USMLE® scores. We recommend discussing this decision with your school’s advising office and with upperclassmen who matched in your target specialty. Taking both exams requires additional study time and exam fees, so weigh the benefits against the costs.
Recommended Study Resources (Free First)
NBOME Practice Exams (COMSAE): The NBOME offers self-assessment exams called COMSAEs for both Level 1 and Level 2-CE. These use retired questions and are the best predictor of your actual exam performance. Take at least one as a diagnostic and one or two more during the final weeks of preparation.
Your School’s OMT/OPP Materials (Free): For the OPP/OMT component, your school’s OMM (Osteopathic Manipulative Medicine) course materials are the primary resource. Review your OMM notes, technique videos, and any provided practice questions. OPP/OMT content is unique to COMLEX-USA® and is not covered by USMLE®-focused study materials.
Khan Academy® (Free): For foundational science review, Khan Academy® covers many of the same topics tested on Level 1 (biochemistry, cell biology, physiology, microbiology). See our Khan Academy® guide.
Anki Flashcard Decks (Free): Community-created Anki decks for COMLEX-USA® include OMT-specific content alongside standard biomedical science material. Use spaced repetition daily. See our spaced repetition guide.
Question Banks (Paid): Most DO students use at least one commercial question bank. Some question banks are specifically designed for COMLEX-USA® and include OPP/OMT content; others are USMLE®-focused with supplemental osteopathic material. We do not recommend specific products and do not place affiliate links. Choose based on recommendations from upperclassmen at your school.
Study Strategies
For Level 1: Follow a similar study structure to USMLE® Step 1 preparation (4 to 8 weeks of dedicated study, combining content review, question bank practice, and spaced repetition), but add daily OMT/OPP review. Budget at least 20 to 30 minutes per day specifically for osteopathic content, including technique review, Chapman’s points, viscerosomatic reflexes, and craniosacral mechanisms. Know the indications and contraindications for each major OMT technique, and be able to identify somatic dysfunction by region based on TART criteria (tenderness, asymmetry, restriction of motion, tissue texture changes).
For Level 2-CE: Follow a similar structure to USMLE® Step 2 CK preparation (3 to 6 weeks of dedicated study, driven primarily by practice questions) with integrated OPP/OMT review. Because Level 2-CE is a two-day exam with more questions, plan your study blocks and practice sessions accordingly. Know the osteopathic approach to common clinical conditions and when OMT is indicated or contraindicated. Pay special attention to the osteopathic management of conditions in which OMT has evidence-based support, such as low back pain, headaches, and certain respiratory conditions.
For the broader context of osteopathic medical education, see our DO pathway page and the physician (MD/DO) career profile. For comparisons between MD and DO training, see our MD vs. DO comparison page.
References
National Board of Osteopathic Medical Examiners (NBOME). “COMLEX-USA.” NBOME, 2025. https://www.nbome.org/exams-assessments/comlex-usa/. Accessed March 2026.
National Board of Osteopathic Medical Examiners (NBOME). “COMSAE Self-Assessments.” NBOME, 2025. https://www.nbome.org/exams-assessments/comsae/. Accessed March 2026.
American Association of Colleges of Osteopathic Medicine (AACOM). “Osteopathic Medical Education.” AACOM, 2025. https://www.aacom.org/. Accessed March 2026.