As antiretroviral therapy (ART) becomes more available in African countries, the potential for interaction with traditional medicines becomes more important. We carried out a cross-sectional survey among individuals with moderate or advanced HIV disease attending a workplace clinic providing ART in South Africa to determine prevalence of traditional medicine use, source, recommended products and costs. Among 44 clinic attendees (100% male, median age 42 years, 30 taking ART), 37 (84%) reported ever using traditional medicines, 25 obtained from a healer or herbalist, eight from their own fields and four from a pharmacy. Fourteen of the 44 (32%) were currently using traditional medicines, most frequently African potato (9/14) and Aloe vera (3/14). Seven out of 30 persons taking ART (23%) reported currently using traditional medicines. Participants spent 4 - 27 pounds per month on traditional medicines. Traditional medicine use is common among individuals with moderate and advanced HIV disease. Concomitant use with ART has the potential for drug interactions and should be discussed routinely in ART counselling. Further work is warranted to investigate whether commonly used traditional medicines interact with ART in vivo.