Little is known about the economic benefits of providing antiretroviral therapy (ART) for HIV infected patients in sub-Saharan Africa and other resource-limited areas. In South Africa, an increasing number of private sector firms are providing access to ART for their employees. One of the barriers to such action, however, is the lack of available information on the success of ART in restoring workers to full productivity, retaining skilled employees in the workforce, and reducing the costs of medical care and death and disability benefits. HIV infected employees on ART may be absent from work less often than untreated HIV infected employees, but more often than HIV uninfected employees. This study will collect data from an independent HIV/AIDS disease treatment program and a large private sector employer in Johannesburg, South Africa to estimate the benefits and costs for businesses to provide ART to eligible employees.