BACKGROUND: Prediction of thrombotic and bleeding risk is important to optimize antithrombotic therapy after percutaneous coronary intervention. METHODS AND RESULTS: We developed the prediction rules for thrombotic and bleeding events separately in Japanese patients. Derivation and validation cohorts consisted of 4778 patients from CREDO-Kyoto (Coronary Revascularization Demonstrating Outcome Study in Kyoto) registry cohort 2 and 4669 patients from RESET (Randomized Evaluation of Sirolimus-Eluting Versus Everolimus-Eluting Stent Trial) and NEXT (Nobori Biolimus-Eluting Versus Xience/Promus Everolimus-Eluting Stent Trial). Primary thrombotic and bleeding events were a composite of myocardial infarction, definite or probable stent thrombosis or ischemic stroke, and GUSTO (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) moderate or severe bleeding. The prediction rule for thrombosis assigned 2 points for severe chronic kidney disease, atrial fibrillation, peripheral vascular disease, and anemia and 1 point for age ≥75 years, heart failure, diabetes mellitus, and chronic total occlusion. The prediction rule for bleeding assigned 2 points for thrombocytopenia, severe chronic kidney disease, peripheral vascular disease, and heart failure and 1 point for prior myocardial infarction, malignancy, and atrial fibrillation. In derivation and validation cohorts, area under the curve was 0.68 and 0.64, respectively, for thrombosis and 0.66 and 0.66, respectively, for bleeding. In the validation cohort, a high thrombosis risk score (≥4, n=682) was associated with higher 3-year incidence of thrombotic events than a score that was intermediate (2-3, n=1178) or low (0-1, n=2809) (7.6%, 3.7%, versus 2.4%, respectively; P<0.0001). A high bleeding risk score (≥3, n=666) was associated with higher incidence of bleeding than scores that were intermediate (1-2, n=1802) or low (0, n=2201) (8.8%, 4.1%, versus 2.3%, respectively; P<0.0001). Among 682 patients at high thrombotic risk, only 39 (5.7%) had low bleeding risk, whereas 401 (58.8%) had high bleeding risk with very high incidence of bleeding (11.6%). CONCLUSIONS: CREDO-Kyoto thrombotic and bleeding risk scores demonstrated modest accuracy in stratifying thrombotic and bleeding risks; however, a large proportion of patients at high thrombotic risk also had high bleeding risk.