The multidisciplinary team model of HIV care evolved out of necessity due to the diverse characteristics and needs of people living with HIV disease. Though it is now accepted as the international standard of care, it represents a significant departure from methods of care for other infectious diseases, and debate continues regarding the effectiveness of its interventions. The debate has been largely uninformed by data; for example, little is known about the relationship between ancillary support services and primary care outcomes. We hypothesized that support services increase access to and retention in HIV primary care in an inner city public hospital clinic. We conducted a retrospective analysis of clinical data sets on 2,647 patients at the CORE Center, Chicago from 1997-1998 to investigate the relationship between four support services-case management (CM), transportation (TRANS), mental health (MH) and chemical dependency (CD)-and access to and retention in HIV primary care. We found that patients who received each of these services were significantly more likely to receive any care, regular care and had more visits than patients with no service, and retention increased by 15-18%. Female gender, younger age, self-pay status and IDU predicted less regular care. Need for all services was substantial and significantly greater in women. Outcomes improved to the greatest extent among patients who needed and received each service. We conclude that support services significantly increased access to and retention in HIV primary care. Our findings validate the multidisciplinary team model of HIV care, and suggest that health services that are tailored to the express needs of patients lead to better care and improved health outcomes. Further testing of changes in health care delivery to meet the rapidly changing needs of people living with HIV disease and respond to the constantly changing practice of HIV medicine is urgently needed to maintain and extend the advances in HIV care outcomes of the past decade.