Major bleeding complications were investigated in 2,460 patients with 3,684 patient-years of warfarin exposure from 2000 to 2003. The most common indications for anticoagulation were atrial fibrillation (30%), venous thromboembolic disease (28%), and mechanical heart valve prosthesis (15%). Eleven patients had 12 nonfatal major bleeding complications, with no fatal bleeds during the study. The incidence of major bleeding complications was 0.12%/year; there were 0.32 bleeds/100 patient-years of coverage. Of the 12 bleeding events, 5 (42%) were intracranial hemorrhages. The average hospitalization cost per patient was dollar 15,988, and the average length of hospitalization was 6.0 days.