The purpose of this study was to evaluate a six-station ethics objective structured clinical examination (OSCE) on a volunteer sample of 66 medical students and 33 residents from three Ontario medical schools. The internal consistency reliability was 0.46 and the median interrater reliability was 0.675 (range 0.30 to 0.89). The residents' scores were higher than those of the medical students (F = 2.24, 0.046). Also, the scores differed among the three schools (F = 3.19, p = 0.0004). The ethics OSCE has adequate interrater reliability and construct validity, but low internal consistency reliability. There are differences among the schools that may assist in ethics curriculum evaluation and development.