Background: Expanded access to combination antiretroviral therapy (ART) in the resource-poor setting is dependent on “task-shifting” from doctors to other health care providers. We compared “doctor-initiated-nurse-monitored” care to the current standard of care, “doctor-initiated-doctor-monitored” ART. Methods: A randomised strategy trial to determine whether treatment outcomes of “nurse-monitored” ART were non-inferior to “doctor-monitored” ART was conducted at two South African primary-care clinics. HIV-positive individuals with a CD4 count of <350cells/mm3 or WHO stage 3 or 4 disease were eligible. The primary objective was a composite end-point of treatment limiting events, incorporating mortality, viral failure, treatment-limiting toxicities and visit schedule adherence. Intention-to-treat analyses were performed. This study is registered with ClinicalTrials.gov, NCT00255840. Findings: The hazard ratio for composite failure was 1.09 (95% CI= 0.89-1.33) which lay within the limits for non-inferiority. The analysis was performed on 812 HIV-positive adults with either doctor-(n=408) or nurse-monitored ART (n=404). At baseline 573 (70%) patients were female, 282 (34.7%) had prior AIDS diagnoses and the median CD4 was 164 cells/mm3. After a median follow-up of 24.3 months, deaths (10 vs. 11), virological failures (44 vs. 39), CD4 gain (270 vs. 248 cells/mm3), toxicity failures (68 vs. 66) and program losses (70 vs. 63) were similar in nurse and doctor arms respectively. 371(46%) patients reached an endpoint of treatment failure; 192(47.5%) and 179(43.9%) in the nurse and doctor arms respectively. Interpretation: Nurse-monitored ART was shown to be non-inferior to doctor-monitored therapy. This study supports task-shifting to appropriately trained nurses for monitoring ART.