Co-infection with GB virus C (GBV-C) in HIV-1-infected individuals could have a beneficial influence on disease outcome. We followed 157 HIV-1-infected patients with seroconversion dates defined within +/-1 year for a median of 7 years. Of these patients, 36 (23%) were positive for GBV-C RNA. Life-table analyses showed no significant difference in outcome variables between patients with or without GBV-C viraemia. Endpoints were CD4 T lymphocyte count of 200 cells/mul or less, AIDS diagnosis and AIDS-related death.