Background:The effect of body weight (BW) on bleeding and ischemic events has not been adequately evaluated in real-world percutaneous coronary intervention (PCI) practice.Methods and Results:12,690 consecutive patients undergoing first PCI in the CREDO-Kyoto registry cohort-2 were divided into 3 groups according to tertiles of BW stratified by sex (male; Tertile 1 <60.0 kg, 2 60.0–68.0 kg, and 3 >68.0 kg, and female; Tertile 1 <47.9 kg, 2 47.9–55.8 kg, and 3 >55.8 kg). Cumulative 5-year incidences of the primary bleeding (GUSTO moderate/severe) and ischemic (myocardial infarction/ischemic stroke) endpoints increased incrementally with decrease in BW in both strata (male Tertiles 1, 2, and 3: 13.7%, 10.3%, and 8.0%, P<0.001, and 13.9%, 11.3%, and 10.2%, P<0.001; female Tertiles 1, 2, and 3: 17.9%, 12.9%, and 10.1%, P<0.001, and 17.9%, 12.9%, and 10.1%, P<0.001). Compared with Tertile 3, the adjusted risks of Tertile 1 for the primary bleeding and ischemic endpoints remained significant in the female stratum (hazard ratio (HR): 1.45, 95% confidence interval (CI): 1.14–1.87, P=0.003, and HR:1.49, 95% CI:1.13–1.95, P=0.004), but not in the male stratum (HR:1.10, 95% CI:0.92–1.32, P=0.31, and HR:1.06, 95% CI:0.90–1.27, P=0.47).Conclusions:Cumulative incidences of bleeding and ischemic events increased incrementally as BW decreased in both men and women. The adjusted risks of underweight relative to overweight for bleeding and ischemic events were significant only in women.