Huang YS, et al. - The effect of peer influence on computed tomography use by Emergency Physicians (EPs) for patients with headache was examined. In addition, researchers evaluated the peer influence effect in EPs with different levels of risk tolerance. A before- and after-retrospective case review was conducted, and the Risk-Taking subscale of the Jackson Personality Index was administered to attending physicians. Findings revealed that for patients with isolated headache, peer influence seemed to be an effective way to improve computed tomography (CT) use rate and Emergency Department length of stay (LOS), especially for most risk-tolerant physicians. The development of appropriate guidelines assisting ED physicians' CT use could be enhanced in assistance of the findings.