Renal dysfunction is a severe complication of advanced HIV disease. We evaluated the impact of highly active antiretroviral therapy (HAART) on renal function among HIV-infected Ugandans in the Home-Based AIDS Care clinical trial. The patients presented with symptomatic HIV disease or CD4 cell count < or = 250 cells/mm(3) and creatinine clearances above 25 ml/min determined by the Cockcroft-Gault equation. Of the 508 patients at baseline, 8% had a serum creatinine over 133 micromol/l and about 20% had reduced renal function evidenced by a creatinine clearance between 25 and 50 ml/min. After 2 years of HAART, the median serum creatinine was significantly decreased by 16% while the median creatinine clearance significantly increased 21%. The median creatinine clearance of patients with renal dysfunction at baseline, increased by 53% during 2 years of treatment. In multivariable analysis, a baseline creatinine above 133 micromol/l, a weight gain of more than 5 kg over the 2 years, female gender and a WHO stage 4 classification were all associated with greater improvements in creatinine clearance on HAART. Our study shows that renal dysfunction was common with advanced HIV disease in Uganda but this improved following 2 years of HAART.