Objective: The aim of this randomized, controlled pilot study was to examine the impact of a pharmacist operated adherence clinic on adherence to highly active antiretroviral therapy (HAART) and viral suppression in patients with HIV over 28 weeks., Methods: Consecutive eligible patients initiating HAART at an indigent-care clinic were randomized to an adherence clinic or to standard care (information provided by physician or nurse practitioner) for education and monitoring. Group assignment was stratified before randomization according to regimen complexity and potential tolerability. Adherence (electronic monitoring and patient self-report) and viral load (reverse-transcription polymerase chain reaction) were assessed at weeks 4, 16, and 28., Results: Thirty-three randomized patients (adherence clinic, n = 16; standard care, n = 17) comprised the intent-to-treat population. The groups were well-matched for demographics and antiretroviral regimen. The median age was 38.0 years in both groups. Most patients were male (85%), had previously used HAART (78%), and had an AIDS diagnosis (79%). Mean (SD) adherence at weeks 4, 16, and 28 was 86% (27%), 77% (28%), and 74% (31%) in the adherence clinic group versus 73% (32%), 56% (39%), and 51% (41%) in the standard care group (week-16 difference, 21% [90% CI, 1%-42%]; week-28 difference, 23% [90% CI, 1%-44%]). Sixty-nine percent of patients in the adherence clinic group took their medication on schedule versus 42% in the standard care group (P = 0.025); mean decline in adherence from weeks 4 to 28 was 12% in the adherence clinic group (P = 0.15) versus 22% in the standard care group (P = 0.002). HIV-1 RNA levels were <400 copies/mL at weeks 4, 16, and 28 in 63%, 100%, and 94% of the adherence clinic group and 29% (P = NS), 71% (P = 0.04), and 65% (P = NS) of the standard care group., Conclusions: In this preliminary trial, an adherence clinic model improved adherence to HAART and virologic response over 28 weeks in the patients studied.