Compared with heparin induced thrombocytopenia (HIT), glycoprotein (GP) IIb/IIIa inhibitor induced thrombocytopenia is characterized by a rapid and profound fall in the platelet count. In severe cases, the platelet count decreases below 20,000/mm3 within the initial 24 hours after exposure to the drugs. It is often associated with severe bleeding complications. Tirofiban is one of the GP IIb/IIIa inhibitors. A case of severe thrombocytopenia in a 60-year-old man, with chronic renal failure (CRF) and acute myocardial infarction (AMI), was recently experienced. Tirofiban was administered to treat the AMI without ST segment elevation. The platelet count fell to 1,000/mm3 with hemoptysis and petechiae 80 hours after the initiation of tirofiban infusion. In this case, the clinical course was similar to that of the typical GP IIb/IIIa inhibitors induced thrombocytopenia, with the exception that its onset time was unusually delayed. The platelet count was normalized in 9 days after cessation of tirofiban infusion. Thus, this unusual case is reported as delayed onset tirofiban induced thrombocytopenia in a CRF patient.