Objectives: To assess outcomes over the first 7 years of antiretroviral therapy (ART) at Themba Lethu Clinic, Johannesburg, South Africa. Design: Observational cohort study. Methods: Patients are managed according to South African National Treatment Guidelines. Mortality is ascertained through linkage with the national vital registration system. Loss to follow-up is defined as at least 3 months late for the last scheduled appointment. Results: Between April 2004 and March 2010, 13 227 patients initiated ART, increasing from 1794 in the year 2004/2005 to 2481 in 2009/2010. Median CD4 cell count at ART initiation increased 39% between 2004 and 2009 (82 vs. 114 cells/ml). The proportion who died within 1 year on ART was below 11% at all time points, whereas the proportion lost by 1 year increased from 8.5% in 2004 to 12.1% in 2009 [risk ratio (RR) 1.42, 95% confidence interval (CI) 1.18–1.71]. We followed the 1794 patients initiated in April 2004 and March 2005 through August 2011 for 8172 person-years. We estimated 25% of patients were lost and 16% died. The overall mortality rate was 3.59 per 100 person-years (95% CI 3.20–4.02). Of the 1577 who completed at least 6 months of follow-up, 213 (13.5%) failed first-line treatment in a median (interquartile range) of 25.9 (15.8–41.4) months on treatment. Of those who failed, 141 (66.2%) switched to second-line for a rate of 48.5 per 100 person-years (95% CI 41.1–57.2). Conclusion: Despite some improvements over 7 years, more intervention is needed in the first year on treatment to reduce overall attrition.