OBJECTIVE There are international calls for improving education for health care workers around certain core competencies, of which patient safety and quality are integral and transcendent parts. Although relevant teaching programs have been developed, little is known about how best to assess their effectiveness. The objective of this work was to develop and implement an objective structured clinical examination (OSCE) to evaluate the impact of a patient safety curriculum. METHODS The curriculum was implemented in a family medicine residency program with 47 trainees. Two years after commencing the curriculum, a patient safety OSCE was developed and administered at this program and, for comparison purposes, to incoming residents at the same program and to residents at a neighboring residency program. RESULTS All 47 residents exposed to the training, all 16 incoming residents, and 10 of 12 residents at the neighboring program participated in the OSCE. In a standardized patient case, error detection and error disclosure skills were better among trained residents. In a chart-based case, trained residents showed better performance in identifying deficiencies in care and described more appropriate means of addressing them. Third year residents exposed to a "Systems Approach" course performed better at system analysis and identifying system-based solutions after the course than before. CONCLUSIONS Results suggest increased systems thinking and inculcation of a culture of safety among residents exposed to a patient safety curriculum. The main weaknesses of the study are its small size and suboptimal design. Much further investigation is needed into the effectiveness of patient safety curricula.