A non-blinded randomized controlled trial evaluated efficacy of pharmaceutical care (PC) (Dáder method) on self-reported antiretroviral adherence and undetectable plasma viral load (UPVL), compared with usual care (UC) in HIV-positive patients in Brazil. Most were male (63 %), mean age 40.3 years (SD = 10). After 12 months, 79.8 % of those receiving PC versus 73.8 % in UC were adherent (RR 1.05, 95 % CI 0.95–1.15, P = 0.35), and 50.3 versus 49.8 % (PC vs. UC, respectively) had UPVL (RR 1.08, 95 % CI 0.97–1.20, P = 0.15). Factors associated with self-reported adherence were regular employment, UPVL, no depressive symptoms, and lower pill load in the treatment regimen. Older age, education, CD4 count <200 cells/mm3, and shorter treatment duration were associated with UPVL. Of 94 reported drug-related problems, 43 % resolved. In subgroup analyses of patients who experienced therapeutic failure and who were non-adherent at the beginning of the trial (N = 50), no differences were found in UPVL (HR 1.35, 95 % CI 0.57–3.19). Only education level (>12 years) was independently predictive of viral suppression (HR 7.47, 95 % CI 1.69–32.91). In conclusion, PC was not associated with increased self-reported adherence to ART or UPVL in patients treated at a health care facility in southern Brazil. The study suggests, however, that PC could be effective for the subgroup of patients with poor adherence.