This controlled trial evaluated the effect of simulation training on patient safety during elective procedures, such as endoscopy and lumbar puncture. Clinicians who had completed simulation training in these procedures were more likely to carry out appropriate evaluation and monitoring during and after sedation than clinicians who had received standard training. Although the study did not measure patient outcomes directly, the results provide support for the growing field of simulation in health care. A previous commentary discusses current applications and approaches to simulation as an educational tool.