BACKGROUND AND OBJECTIVES: Recent randomized studies have shown a significant reduction in the rate of recurrent cardiac events with adjunctive pharmacotherapy, using Glycoprotein IIb/IIIa inhibitors (GPI), in patients undergoing percutaneous coronary intervention (PCI) procedures. However, in Korea, there is a paucity of data concerning complications of tirofiban therapy in patients with acute coronary syndrome (ACS). Therefore, this study was performed to evaluate the safety of tirofiban therapy. SUBJECTS AND METHODS: ACS patients who underwent tirofiban administration between May 2002 and October 2003 were reviewed. The rates of bleeding, transfusion, and thrombocytopenia were analyzed, and the rates of complications by ages, gender and PCI compared with medical treatment, renal function and vascular access route. RESULTS: A total of 261 ACS patients (male/female=150/111) underwent tirofiban therapy. The mean ages of the subjects was 64.5 years, the rates of minor bleeding, major bleeding, transfusion and thrombocytopenia were 8.1% (n=21), 2.3% (n=6), 4.6% (n=12) and 1.2% (n=3), respectively. Minor bleeding occurred at similar rates in both sexes (8 vs. 8.1%) and to a greater extent in old age (> or =65) (12.5 vs. 2.6%, p=0.093), but major bleeding occurred to a greater extent in females and old age (5.4 vs. 0% and 4.2 vs. 0%, p=0.25 and 0.093, respectively). The rates of thrombocytopenia and transfusion were greater in old age (2.1 vs. 0% and 8.3 vs. 0%, p=0.052 and 0.087, respectively). In-hospital days were greater in old age (14.7+/-9.5 vs. 11.9+/-4.4 days, p=0.065). The rates of complications were similar in both groups when compared by PCI or medical treatment and vascular access route. The serum creatinine was 3.3 mg/dL in those with major bleeding, which was higher than in the other groups (p=0.000). CONCLUSION: The tirofiban therapy in patients with ACS did not induce an increase in the bleeding rates, in-hospital days and it was safe and well tolerated in old age.