Although physician impairment may have substantial personal and clinical consequences, it is commonly held that physicians fail to act in the case of impaired colleagues. To learn about initial responses when confronted with impaired house officers and attending physicians, we administered five case scenarios to all 76 internal medicine house officers at a large, urban, teaching hospital. House officer responses to an alcohol-impaired physician differed depending on whether that physician was an attending physician or a house officer. Seventy-two percent of house officers would tell the chief resident about the alcohol-impaired attending physician, whereas 96% would confront the alcohol-impaired house officer personally. The most common response to the incompetent attending physician (67%) and the incompetent house officer (49%) was to tell the chief resident; only 25% would confront an incompetent house officer. In contrast, 71% would confront a depressed house officer.