Abstract: AIM: To study the short-term efficacy and safety of a high maintenance dose (150 mg) of clopidogrel in treating patients undergoing drug-eluting stent (DES) implantation. METHODS: One hundred twenty consecutive patients undergoing DES implantation in our hospital from January 2007 to December 2007 were enrolled in the study. A 600-mg loading dose was administered before percutaneous coronary intervention (PCI). Patients were then randomized to receive clopidiogrel 75 mg (n=60) or 150 mg (n=60) per day for 30 days. From 31 days to 12 months after surgery, all patients received 75 mg/day clopidogrel. Adenosine diphosphate (ADP)-induced maximal platelet aggregation rate (MPAR) was measured before PCI and 15 and 30 days after PCI. The incidence of major clinical cardiovascular events (including death, myocardial infarction, target vessel revascularization, stroke) and hemorrhagic events were followed up to 30 days and 9 months. RESULTS: Although no significant difference was observed in ADP-induced MPAR between the 75-mg group and 150-mg group before PCI, significantly decreased platelet aggregation rate was seen in the 150-mg group (P<0.05) at 15 days and 30 days after PCI. The incidence of major clinical cardiovascular events after 30 days and after 9 months in 150-mg group was significantly lower than in the 75-mg group (P<0.05; P<0.01). The occurrence of 30-day and 9-month hemorrhagic events between groups had no significant difference. CONCLUSION: Treatment with a high maintenance dose (150 mg) of clopidogrel after PCI is more efficient in inhibiting platelet aggregation than treatment with 75 mg dose. A high clopidogrel maintenance dose of 150 mg daily for the first month after PCI procedure following a 600-mg loading dose reduces the risk of adverse events in patients undergoing DES implantation and significantly improves clinical outcomes.