Intense work demands, limited control, and a high degree of work-home interference abound in residency training programs and should strongly predispose resident physicians to burnout as they do other health care professionals. This article reviews studies in the medical literature that address the level of burnout and associated personal and work factors, health and performance issues, and resources and interventions in residents. MEDLINE and PubMed databases were searched for peer-reviewed, English-language studies reporting primary data on burnout or dimensions of burnout among residents, published between 1983 and 2004, using combinations of the Medical Subject Heading terms burnout, professional, emotional exhaustion, cynicism, depersonalization and internship and residency, housestaff, intern, resident, or physicians in training and by examining reference lists of retrieved articles for relevant studies. A total of 15 heterogeneous articles on resident burnout were thus identified. The studies suggest that burnout levels are high among residents and may be associated with depression and problematic patient care. However, currently available data are insufficient to identify causal relationships and do not support using demographic or personality characteristics to identify at-risk residents. Moreover, given the heterogeneous nature and limitations of the available studies, as well as the importance of having rigorous data to understand and prevent resident burnout, large, prospective studies are needed.