Between January 1994 and October 1997, we interviewed 2576 black in-patients with newly diagnosed cancer in Johannesburg and Soweto, South Africa. Blood was tested for HIV-1 and HHV-8 antibodies and the study was restricted to 2191 HIV-1 antibody-negative patients. We examined the relationship between infection with HHV-8 and sociodemographic and behavioural factors using unconditional logistic regression models. Of the 2191 HIV-1 negative patients who did not have Kaposi's sarcoma, 854 (39·1%) were positive for antibodies against the latent nuclear antigen of HHV-8 encoded by orf73 in a immunofluorescence assay. Infection with HHV-8 was independently associated with increasing age (P trend=0·02). For females, independent risk factors also included working in a paid domestic capacity (OR 1·63, 95% CI 1·09–2·44, P=0·02), defining occupational status as economically non-active unemployed (OR 1·70, 95% CI 1·06–2·72, P=0·03), having a state pension or being on a disability grant (OR 1·49, 95% CI 1·05–2·11, P=0·02), using oral contraceptives (OR 1·43, 95% CI 1·03–1·99, P=0·03) and having a delayed age at menarche (P trend=0·04). The relationship between these variables and HHV-8 antibody status requires further, prospective study.