Physician gender has been viewed as a possible source of variation in the interpersonal aspects of medical practice, with speculation that female physicians facilitate more open and equal exchange and a different therapeutic milieu from that of male physicians. However, studies in this area are generally based on small samples, with conflicting results. To systematically review and quantify the effect of physician gender on communication during medical visits. Online database searches of English-language abstracts for the years 1967 to 2001 (MEDLINE, AIDSLINE, PsycINFO, and Bioethics); a hand search was conducted of reprint files and the reference sections of review articles and other publications. Studies using a communication data source, such as audiotape, videotape, or direct observation, and large national or regional studies in which physician report was used to establish length of visit, were identified through bibliographic and computerized searches. Twenty-three observational studies and 3 large physician-report studies reported in 29 publications met inclusion criteria and were rated. The Cohen d was computed based on 2 reviewers' (J.A.H. and Y.A.) independent extraction of quantitative information from the publications. Study heterogeneity was tested using Q statistics and pooled effect sizes were computed using the appropriate effects model. The characteristics of the study populations were also extracted. Female physicians engage in significantly more active partnership behaviors, positive talk, psychosocial counseling, psychosocial question asking, and emotionally focused talk. There were no gender differences evident in the amount, quality, or manner of biomedical information giving or social conversation. Medical visits with female physicians are, on average, 2 minutes (10%) longer than those with male physicians. Obstetrics and gynecology may present a different pattern than that of primary care, with male physicians demonstrating higher levels of emotionally focused talk than their female colleagues. Female primary care physicians engage in more communication that can be considered patient centered and have longer visits than their male colleagues. Limited studies exist outside of primary care, and gender-related practice patterns in some subspecialties may differ from those evident in primary care.