By December 2003, the estimated adult HIV/AIDS prevalence rate in sub-Saharan Africa was 7.5-8.5%, and rates of herpes simplex virus type-2 (HSV-2) infection among adults aged >30 years ranged from 60% to 82%. However, little is known about the natural history of HIV/HSV-2 co-infection in this population. We evaluated HIV viral load and CD4+ cell counts among persons with and without chronic HSV-2 co-infection in a cross-sectional study of HIV-infected persons not receiving antiretroviral therapy. HSV-2 and HIV co-infection was associated with a 0.3 log copies/mL higher HIV viral load compared with persons without HSV-2 infection (P=0.014). Chronic HSV-2 infection may have a negative effect on the clinical course of persons with HIV.