本文報告一位患有輕微中風曾經使用warfarin 6 個月來預防血栓形成的病人，在進行心臟瓣膜手術後再度開始服用warfarin，20 天後肝臟酵素及膽紅素明顯持續上升，病人臨床表現有鞏膜及皮膚泛黃、茶色尿液、倦怠以及食慾不振。術後31天，alanine aminotransferase (ALT)：199 U/L、 alkaline phosphatase (ALK－P)：1004 U/L、Total bilirubin：27.1 mg/dL。在停用warfarin 改用heparin 2 天後，病患精神恢復且食慾明顯增加。Warfarin 停藥28 天後，ALT 降為75 U/L、ALK－P：676 U/L、Total bilirubin：15.2 mg/dL。因為病患要求出院，故停用heparin，再次換回warfarin使用。出院7 天後，生化血液檢查值又向上攀升，ALT：112 U/L、ALK－P：747 U/L、Total bilirubin：22.3 mg/dL，因而懷疑為藥物引發之不良反應。

We report a case who had previously been using warfarin for about 6 months to prevent thrombus formation after CVA attack. He was put on to warfarin again after a revised cardiac valve replacement surgery. Twenty days after surgery, the patient had sclera icteric, jaundice, anorexia and tea-colored urine, and the liver enzyme and total bilirubin levels were elevated significantly. Thirty-one days after surgery, the biochemistry data showed alanine aminotransferase (ALT) was 199 U/L, alkaline phosphatase (ALK-P) was 1004 U/L, and total bilirubin was 27.1 mg/dL. Warfarin was then discontinued and heparin was used instead. Two days later, the patient felt better with improved appetite. Four weeks after stopping warfarin, the ALT dropped to 75 U/L, ALK-P 676 U/L, and total bilirubin 15.2 mg/dL. Because the patient wished to discharge, we switched heparin to warfarin again. Seven days after discharge, his liver function tests were deteriorated again ALT: 112 U/L, ALK-P: 747 U/L, total bilirubin: 22.3 mg/dL. This is suspected to be a case of warfarin induced hepatotoxicity.