Abstract： Objective To evaluate the efficacy of a 300 mg loading dose of clopidogrel followed by 150 mg as maintenance dose in patients with percutaneous coronary intervention (PCI).Methods A total of 108 consecutive patients undergoing elective PCI were recruited from our hospital from July 2007 to July 2008.A 300 mg loading dose was administered prior to PCI. Then they were randomized to receive clopidogrel75 mg (n =55) or 150 mg (n =46) daily for 30 days.From Day 30 to Month 6 post-operation,all of them received 75 mg/d clopidogrel and were followed up for a mean period of 6 months.Results Thirty days after PCI,the platelet inhibition of the 150 mg group was significantly higher than the 75 mg group (64.2％ ± 13.3％ vs 52.6％ ± 14.3％,P =0.00).The ratios of fatal or non-fatal myocardial infarction (MI) ( 1 ( 1.8％ ) vs 3 ( 6.5％ ),P =0.405 ) and target vessel revascularization (TVR) (4 (7.2％ ) vs 6 (13.0％),P =0.714) were significantly lower in the 150 mg group than those in the 75 mg group.So the overall incidence of MACE including death,MI and TVR was obviously lower in the 150 mg group than that in the 75 mg group ( 13.0％ vs 20.2％,absolute risk reduction 7.3％ ).Condusion A high clopidogrel maintenance dose of 150 mg daily for the first month after PCI reduces the risk of long-term adverse events in patients with elective percutaneous coronary intervention.