Background: Despite widespread use of problem-based learning (PBL) in medical schools, no review currently exists on its assessment. Given the importance of assessment for any curriculum, a critical review of the literature was conducted to explore whether the assessment methods match the philosophical tenets of PBL. Summary: Articles from MEDLINE and other databases on the assessment of PBL were reviewed. The following areas require special attention by PBL medical schools: enhancement of formal continuous formative assessment; use of the context of a working problem to assess knowledge and problem-solving skills; prevention of negative steering effects by a judicious choice of assessment content, instruments, and timing; and implementation of a longitudinal and centralized student profile. Conclusion: Despite the existence of general practical recommendations on assessment in PBL settings, this review reveals a lack of uniformity and consensus on the practical application of general principles. Topics for future research are highlighted.