Coumarin is a drug which is extensively used to treat lymphedema. We report two cases of acute hepatitis probably due to coumarin. Two women, 40 year and 45 year-old, were treated with 90 mg/d of coumarin for 5 months. Clinical features included jaundice, pruritus, and diarrhea. A marked increase in serum aminotransferases was observed (ALT: 30 and 100 times the upper limit of normal, respectively). Coumarin withdrawal was rapidly followed by a favorable outcome in both cases. Rechallenge in one case induced a relapse of symptoms and liver test abnormalities. Coumarin can induce acute cytolytic hepatitis.