Concerns that standard didactic adherence counselling may be inadequate to maximise antiretroviral therapy (ART) adherence led us to evaluate more intensive individualised motivational adherence counselling. We randomised 297 HIV-positive ART-naïve patients in Durban, South Africa, to receive either didactic counselling, prior to ART initiation (n = 150), or an intensive motivational adherence intervention after initiating ART (n = 147). Study arms were similar for age (mean 35.8 years), sex (43.1 % male), CD4+ cell count (median 121.5 cells/μl) and viral load (median 119,000 copies/ml). Virologic suppression at 9 months was achieved in 89.8 % of didactic and 87.9 % of motivational counselling participants (risk ratio [RR] 0.98, 95 % confidence interval [CI] 0.90–1.07, p = 0.62). 82.9 % of didactic and 79.5 % of motivational counselling participants achieved >95 % adherence by pill count at 6 months (RR 0.96, 95 % CI 0.85–1.09, p = 0.51). Participants receiving intensive motivational counselling did not achieve higher treatment adherence or virological suppression than those receiving routinely provided didactic adherence counselling. These data are reassuring that less resource intensive didactic counselling was adequate for excellent treatment outcomes in this setting.