The major risk factors for the transmission of hepatitis C virus (HCV) have been sharing needles for intravenous drug use (IDU) and receiving blood and blood products; however, recent findings suggest that HCV is being increasingly sexually transmitted, particularly among HIV-positive men who engage in high-risk, unprotected sexual behaviors with other men. Sixteen HIV-positive patients were diagnosed with sexually acquired HCV infection at a leading London HIV outpatient treatment center during 2002. All 16 patients were homosexual males with no history of IDU who had been involved in high-risk, unprotected sexual behaviors, which included active and passive anal intercourse, fisting, rimming, and oral sex. Six patients (37.5%) in the cohort spontaneously cleared HCV infection and consequently tested negative for HCV RNA. The remaining 10 patients were all started on HCV treatment, which consisted of pegylated interferon alpha-2b in combination with ribavirin. Three patients (43%) have achieved a significant reduction in HCV RNA after 12 to 24 weeks of HCV treatment. The earlier HCV seroconversion is detected and treated, the better the chance of achieving viral eradication.