OBJECTIVES: As the use of complementary and alternative medicine (CAM) has increased in the general population, so has the interest in CAM education among medical students and medical educators. The purpose of this study is to determine the impact of a CAM workshop using standardized patients (SP) on knowledge and clinical skills of third-year medical students. DESIGN: A 4-hour CAM workshop was developed as part of a new curriculum for a required third-year 4-week primary care internal medicine clerkship. The CAM workshop and 3 other novel workshops were randomized for delivery to half of the rotational groups. The CAM workshop incorporates 4 SP cases representing different clinical challenges. All students in every rotation group are assigned CAM readings. At the end of the rotation, all students take a 100-item written exam (7 CAM items) and 9-station SP exam (1 CAM station) including a post-SP encounter open-ended written exercise. Scores on the written exam CAM items, CAM SP checklist, and CAM open-ended written exercise of workshop participants and nonparticipants were analyzed with simple means, standard deviations, and multiple regression approaches. RESULTS: The CAM workshop was delivered to 12 of the 24 rotation groups during the 2004-2005 and 2005-2006 academic years. Ninety-two students participated in the workshop, and 94 did not. Workshop participants performed significantly better than nonparticipants on the CAM-specific SP checklist items (58 vs 36.6%, P<.0001), post-SP encounter written exercise (76.9 vs 63.3%, P<.0001), and 7 CAM written exam items (84.8 vs 76.3%, P<.0001). CONCLUSIONS: Students participating in a 4-hour SP workshop exhibit superior CAM knowledge as assessed by SP checklist, open-ended exercises, and multiple choice items. It appears that practice with SPs assists in acqusition and application of CAM knowledge and deferential counseling skills.