PURPOSE To describe how communication failures contribute to many medical mishaps. METHOD In late 1999, a sample of 26 residents stratified by medical specialty, year of residency, and gender was randomly selected from a population of 85 residents at a 600-bed U.S. teaching hospital. The study design involved semistructured face-to-face interviews with the residents about their routine work environments and activities, the medical mishaps in which they recently had been involved, and a description of both the individual and organizational contributory factors. The themes reported here emerged from inductive analyses of the data. RESULTS Residents reported a total of 70 mishap incidents. Aspects of "communication" and "patient management" were the two most commonly cited contributing factors. Residents described themselves as embedded in a complex network of relationships, playing a pivotal role in patient management vis-à-vis other medical staff and health care providers from within the hospital and from the community. Recurring patterns of communication difficulties occur within these relationships and appear to be associated with the occurrence of medical mishaps. CONCLUSION The occurrence of everyday medical mishaps in this study is associated with faulty communication; but, poor communication is not simply the result of poor transmission or exchange of information. Communication failures are far more complex and relate to hierarchical differences, concerns with upward influence, conflicting roles and role ambiguity, and interpersonal power and conflict. A clearer understanding of these dynamics highlights possibilities for appropriate interventions in medical education and in health care organizations aimed at improving patient safety.