This study aimed to compare major hemorrhage rates among patients receiving warfarin, acetylsalicylic acid (ASA), and clopidogrel to those receiving ASA and clopidogrel following percutaneous coronary intervention with stent implantation. This retrospective cohort study identified patients with stents implanted between September 1, 2003 and December 31, 2006. Patients treated with warfarin, ASA, and clopidogrel within 30 days of hospital discharge (Triple Therapy group) were matched by age, sex, and stent type to patients treated with ASA and clopidogrel (Dual Therapy group). Outcomes included the incidence rates of major hemorrhage and major adverse coronary events (MACE) within 12 months of stent implantation. There were 175 and 339 patients in the Triple Therapy and Dual Therapy groups, respectively. There were 25 (14.3%) and 10 (3.0%) major hemorrhages in the Triple Therapy and Dual Therapy groups, respectively (OR 9.0; 95% CI, 3.1-26.1). Patients in the Triple Therapy group had a greater likelihood of MACE compared to patients in the Dual Therapy group (OR 2.0; 95% CI 1.1-3.8). Post-stent treatment with warfarin, ASA, and clopidogrel was associated with a substantially greater likelihood of major hemorrhage than treatment with ASA and clopidogrel alone.