Medical care for human immunodeficiency virus (HIV)-infected persons has grown increasingly complex, yet few studies have examined experienced HIV physicians' views about current HIV medical care. The objective of this study was to examine the relationship between physicians' HIV experience, self-perceived expertise, and confidence with providing 18 aspects of HIV medical care and between confidence in aspects of care and medical specialty. At geographically diverse, HIV continuing medical education programs conducted in the fall of 1999, 359 currently practicing HIV physicians completed a written survey measuring participants' demographic characteristics, experience, HIV expertise, and level of confidence providing essential aspects of HIV care. Participants currently managed a median of 50 HIV-infected patients with a career total of 300. Significant correlations were found between experience and expertise items and experience and 15 of 18 confidence items. Confidence levels varied from 11% to 85% highly confident across 18 aspects of HIV care. Physicians' confidence with providing aspects of HIV care varied by the three predominant specialty groups (infectious diseases, internal medicine, and family practice/general medicine). Physicians who have informally specialized in HIV care reported a range of self-perceived expertise and confidence, indicating the complexity of HIV medical care today. Our results suggest that even the most experienced HIV physicians in the United States continue to benefit from more experience and that each medical specialty examined in this study brings its own set of skills needed to provide optimal HIV care. This study constitutes a first step toward defining and formalizing HIV medical care.