Backgound and objectives: Combination of clopidogrel or ticlopidine in addition to aspirin has been accepted as a standard regimen after coronary stenting. Clopidogrel have less serious side effects such as neutropenia and thrombotic thrombocytopenic purpura than ticlopidine and has been substituted ticlopidine. But it is still controversial whether clopidogrel is as effective as ticlopidine against the thrombotic complications after stenting. This is a prospective randomized study to compare the efficacy and safety of clopidogrel plus aspirin (CA) with ticlopidine plus asprin (TA) after elective coronary stenting. Materials and Methods: From October 2000 to March 2003, three hundred patients were enrolled in this study. Patients were randomly assigned to receive either CA (n=150, 300mg loading dose and 75mg qd) or TA (n=150, 500mg loading dose and 250mg bid) after diagnostic angiography. Each drug was maintained after loading dose for one to three days before stenting and for 1 month after stenting. The primary end point was a composite of angiographic stent thrombosis, death, myocardial infarction, target lesion revascularization (TLR) and stroke within 6 month. The secondary end points were hemorrhagic vascular complications, or drug side effects such as neutropenia, thrombocytopenia, or any side effects requiring cessation of drugs. Results: After randomization, 25 patients were excluded from the analysis竊�13 balloon angioplasty alone, 9 inadequate results after stenting, 3 follow-up loss (TA 14, CA 11). There were no significant differences in the baseline clinical and angiographic characteristics. The primary end point was reached in 11 patients (7.9%, subacute thrombosis(1),stroke(1),TLR(8) ) in CA group and 15 patients (11%, death(1), SAT(1), stroke(1), TLR(10)) in TA group (p竊�0.42). The rate of hemorrhagic-vascular complications was not different between the groups (1.4% vs 2.0%, p竊�1.0). A patient developed transient asymptomatic neutropenia in the TA group but recovered after cessation of ticlopidine. Conclusion : There were no significant differences in the rate of thrombotic complication and major cardiac adverse events within 6month after coronary stenting between CA and TA group.