A 54-year-old man with chronic hepatitis C virus (HCV) developed quadrihemianopsia caused by lacunar brain infarction. Extensive evaluation revealed high titers of anticardiolipin antibodies (ACA). Following interferon treatment (6 x 10(6), three times a week for 2 months and 3 x 10(6) for another 7 months), liver transaminase levels decreased to normal, HCV RNA in blood was no longer detectable, concomitantly with the disappearance of the ACA. The patient remained clinically stable without evidence for either HCV activity (RNA) or ACA or further thromboembolic events.