The study determined the nutritional status of adult antiretroviral therapy (ART) recipients, and investigated the association between the duration on ART and the nutritional status. This study was based in primary health facilities in Gauteng, South Africa. The data collected included sociodemographic variables; the duration of the treatment; and the body mass index (BMI), classified as undernutrition (<18.5 kg/m2), normal (18.5–24.9 kg/m2), or overweight/obesity (≥25 kg/m2). ART recipients (n = 480) had a mean age of 35 (± 8.4SD) years. All had taken ART for six months or more (range 6–48 months). The data were analyzed using STATA 13.0. The overall prevalence of overweight/obesity was 39%, it was higher in females (46%) than in males (30%), 26% were overweight, and 13% were obese. Underweight was 13%, and was higher in males (18%) than females (9%). Being overweight was more likely in those aged ≥35 years and those in smaller households. Being obese was less likely in males, in the employed, and in those with a higher income, but was more likely in those with a longer duration on ART. Abdominal obesity was high, but less likely in males. Interventions to prevent overweight/obesity should be integrated into routine HIV care, while at the same time addressing the burden of undernutrition among ART recipients.