Occupational settings offer an ideal opportunity to provide preventive health services for HIV-infected workers. A specialized clinic was established in a mining hospital in the Free State, South Africa, with the primary aim of delivering preventive therapy such as isoniazid to those at high risk of tuberculosis (individuals with HIV infection or silicosis), and cotrimoxazole to those at highest risk for opportunistic infections. The clinic design has taken regard of the importance of minimizing stigma, protecting confidentiality, monitoring potential side effects, supporting adherence and identification of prophylaxis failure. The clinic opened in April 1999 and, by August 2001, 1773 patients had attended at least once; 1762 are HIV-infected and 11 have silicosis. Of those with HIV infection, most were asymptomatic at their first visit. The clinic has achieved high acceptability: 99% of persons who were actively recruited to the service agreed to attend. The number still attending after a median of 13 months from recruitment was 1,270 (72%) and only 48 (2.7%) have declined continued attendance. Most losses were due to termination of employment unrelated to a medical condition. The clinic has already been successfully replicated in two other regions of the mining health service in South Africa and provides a model for workplace HIV clinical services that could be used for implementation of further interventions such as antiretroviral therapy.