AIM: To clarify the prevalence of defensive medicine and the specific defensive medicine practices among gastro-enterologists in Japan.METHODS: A survey of gastroenterologists in Hiroshi-ma, Japan, was conducted by mail in March 2006. The number of gastroenterologists reporting defensive medi-cine behaviors or changes in their scope of practice and the reported defensive medicine practices, i.e., assurance and avoidance behaviors, were examined.RESULTS: A total of 131 (77%) out of 171 gastroenter-ologists completed the survey. Three (2%) respondents were sued, and most respondents (96%) had liability insurance. Nearly all respondents (98%) reported prac-ticing defensive medicine. Avoidance behaviors, such as avoiding certain procedures or interventions and avoiding caring for high-risk patients, were very common (96%). Seventy-five percent of respondents reported often avoiding certain procedures or interventions. However, seasoned gastroenterologists (those in practice for more than 20 years) adopted avoidance behaviors significantly less often than those in practice for less than 10 years. Assurance behaviors, i.e., supplying additional services of marginal or no medical value, were also widespread (91%). Sixty-eight percent of respondents reported that they sometimes or often referred patients to other spe-cialists unnecessarily.CONCLUSION: Defensive medicine may be highly prev-alent among gastroenterologists throughout Japan, withpotentially serious implications regarding costs, access, and both technical and interpersonal quality of care.