Although empirical information on resource use during HIV infection is vital to improving quality of care, the issues involved in conducting research on resource use have received little attention in the medical literature. The purpose of this paper is to review the theoretical and methodological issues of conducting research on health care utilization patterns among persons with HIV/AIDS. Conceptual definitions of utilization are compared and contrasted. Three theoretical frameworks, the Andersen Behavioral Model, the Health Belief Model, and the Biopsychosocial Model are described to illustrate their applicability in future research studies. Research designs, measurement considerations, sampling approaches, and existing data sources on utilization are reviewed. Recommendations for health care utilization research are summarized and highlight the importance of designing studies and generating data for investigation of the factors facilitating patients' use of an optimal array of services including prevention, long-term, and rehabilitation care.