BACKGROUND: Little is known about using the Objective Structured Clinical Examination (OSCE) in physical diagnosis courses. The purpose of this study was to describe student performance on an OSCE in a physical diagnosis course. METHODS: Cross-sectional study at Harvard Medical School, 1997-1999, for 489 second-year students. RESULTS: Average total OSCE score was 57% (range 39-75%). Among clinical skills, students scored highest on patient interaction (72%), followed by examination technique (65%), abnormality identification (62%), history-taking (60%), patient presentation (60%), physical examination knowledge (47%), and differential diagnosis (40%) (p <.0001). Among 16 OSCE stations, scores ranged from 70% for arthritis to 29% for calf pain (p <.0001). Teaching sites accounted for larger adjusted differences in station scores, up to 28%, than in skill scores (9%) (p <.0001). CONCLUSIONS: Students scored higher on interpersonal and technical skills than on interpretive or integrative skills. Station scores identified specific content that needs improved teaching.