We evaluated the effect of high versus low loading doses of clopidogrel in patients with stable angina pectoris who underwent percutaneous coronary intervention (PCI) on periprocedural events, in-hospital complications, and 30-day outcomes. The recommended loading dose of clopidogrel for patients with PCI is currently 300 mg. Recent studies have suggested that 600 mg may decrease periprocedural complications in patients with unstable angina. However, whether this holds for patients with stable angina pectoris is unknown. We reviewed records of 445 patients with stable angina pectoris who underwent PCI and were loaded with 300 mg (n = 126) or 600 mg (n = 319) of clopidogrel immediately before the procedure. Study end points were periprocedural ischemic events, bleeding complications, and a composite of major adverse cardiac events at 30 days. Baseline characteristics and procedural indexes were similar between groups. Major in-hospital complications were recorded in 2 patients in the 600-mg group and in no patient in the 300-mg group (p = 1.00). Postprocedural increase of cardiac enzymes (troponin I, p = 0.91; creatinine kinase-MB, p = 0.395) and major bleeding (0.6% vs 0%, p = 1.00) were comparable, as was 30-day major adverse cardiac events (1.2% vs 0%, p = 0.56). Multivariate analysis did not identify any risk decrease for periprocedural myocardial infarction with 600 mg of clopidogrel (odds ratio 2.68, 95% confidence interval 0.74 to 9.78, p = 0.135). In conclusion, in patients with stable angina pectoris, a 300-mg clopidogrel loading dose, when given immediately before PCI, is sufficient. Although 600 mg was clinically safe, it was not associated with fewer periprocedural events and improved 30-day outcomes compared with 300 mg.