Treatment with highly active antiretroviral therapy (HAART) decreases morbidity and mortality for persons with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and reduces costs of care. Yet many patients for whom HAART is indicated do not receive it. This study investigated the reasons why certain patients of a community health center with HIV/AIDS did not receive HAART between 1997 and 1998. Medical record reviews were performed to determine which patients for whom HAART was indicated (according to United States Public Health Service guidelines) were not prescribed HAART. Chart reviews and patient interviews were conducted to determine why they did not receive HAART. Of the 88 patients eligible for HAART, 60 (69%) had it prescribed in 1997-1998. Of the remaining 28 patients, 3 did not receive HAART because their provider never discussed it with them. For 6 patients (21%), the provider discussed HAART but did not recommend it; 16 patients (57%) declined HAART although their provider recommended it, and 3 (11%) accepted their provider's recommendation but never started HAART. Patients' most common reasons for refusing HAART were not being ready for strict adherence to a complex regimen (7/16) and fear of side effects (6/16). Other reasons included active drug use, religious beliefs, homelessness, confidentiality concerns, depression, and feeling well without HAART. Providers did not recommend HAART because of active drug use (4/6), lack of engagement with care (2/6) as well as homelessness, depression, and the perception that the patient was doing well without HAART. Providers should be trained to offer all patients the opportunity to develop a plan to address barriers to adherence and the support needed to implement it. Resources should also target the treatment of substance abuse and mental illness to improve the usage of HAART.