In a case-control study, we evaluated the relative risk of hepatic vein thrombosis among recent oral contraceptive users as compared with nonusers. Thirty-three cases of hepatic vein thrombosis affecting women aged 15-45 yr were collected between 1970 and 1983, and individually matched to 3 or 4 controls interviewed in 1982-1984. There were 18 recent oral contraceptive users among the 33 cases, and 44 recent oral contraceptive users among the 128 case-matched controls. The relative risk of hepatic vein thrombosis was 2.37 (95% confidence interval: 1.05-5.34, p less than 0.02). The relative risk of hepatic vein thrombosis is close to that of stroke, myocardial infarction, and venous thromboembolism among oral contraceptive users as compared with nonusers.