A 64-year-old man underwent CABG. 18000 unit of bovine lung heparin was used during operation for extracorporeal circulation and small amount of heparin was injected until the 5th postoperative day to keep intravenous line patent. His postoperative course was uneventful until the 10th postoperative day when marked ecchymosis developed on his eyelid. Laboratory data showed marked thrombocytopenia (1.3 x 10(4)/microliters) and disseminated intravascular coagulation. The diagnosis of heparin-induced thrombocytopenia (HIT) was confirmed by platelet aggregation test with heparin. Gabexate mesilate and platelet-concentrates were administered and platelet count returned to normal within a week. HIT usually occurs during administration of heparin. In this case, it occurred 5 days after we stopped heparin. Delayed onset of HIT might be related to delayed metabolism of heparin due to postoperative fluid shift.