Background: High-risk percutaneous coronary interventions (PCI) are associated with high complication rate and low procedural success rate, especially in diabetics. The purpose of this study is to determine long-term clinical benefits of Abciximab in diabetic patients undergoing high-risk PCI with acute ST-elevation myocardial infarction (ASTEMI). Methods: All consecutive 126 ASTEMI patients undergoing high-risk PCI with standard dose abciximab therapy from Feb. 1999 and Feb. 2002 were analyzed. They were divided into two groups, 35 in diabetic group (Group I, 58.6짹8.7 years, 29 male), and 91 in non-diabetic group (Group II, 60.6짹10.4 years, 69 male). MACE [death, myocardial infarction, target vessel revascularization (TVR), CABG] was examined. Results: Baseline clinical characteristics, inflammatory marker, echocardiography parameter, baseline coronary angiographic characteristics were not different between the two groups. The thrombus containing lesion was 97% and total occlusion was 67%. Procedural success was achieved in 91.4% in group I and 93.4% in group II. No significant intracranial bleeding and hemorrhagic event was observed in both groups. No MACE were observed in Group I, but there were 9 (9.9%) of MACE in Group II during hospitalization. Four-year clinical follow-up was performed in 124 patients (98.4%). Death occurred in 4 (11.4%) of patients in the group I and in 9 (9.9%) in the group II (p=0.51), MI in 2 (5.7%) and 5 (5.5%), TVR in 11 (31.4%) and 19 (20.9%) (p=0.15) and CABG in 1 (2.9%) and 2 (2.2%). The number of overall MACE were 14 (40.0%) in Group I and 35 (38.5%) in Group II (p=0.51). Conclusions: The abciximab therapy used in diabetic ASTEMI patients undergoing high-risk PCI was effective in early clinical outcome, but long-term clinical benefits were not maintained.