Bleeding complications of acute coronary syndromes (ACS) after percutaneous coronary intervention (PCI) are strongly associated with adverse patient outcomes, and gastrointestinal bleeding (GIB) is the most common major bleeding event, especially in the early post-PCI period. Current guidelines recommend routinely conducting bleeding risk assessments. The existing tools are mainly used to evaluate the overall bleeding risk and guide the adjustment of antithrombotic strategies after 1 year. However, there are no specific tools for GIB risk assessment.Between January 2015 and June 2015, 4943 ACS patients underwent PCI were consecutively enrolled in the derivation cohort. GIB, cardiovascular, and cerebrovascular events were recorded within 1 year of follow-up. A validation cohort including 1000 patients who met the same inclusion and exclusion criteria was also established by propensity-score matching baseline characteristics. Multivariable cox proportional-hazards regression model was used to derive a risk-scoring system, and predictive variables were selected. A risk score nomogram based on the risk prediction model was created to estimate the 1-year risk of GIB.In this study, we found that the usage of clopidogrel (hazard ratio, HR: 2.52, 95% confidence intervals, CI: 1.573-4.021) and glycoprotein IIb/IIIa receptor inhibitors (HR: 1.863, 95% CI: 1.226-2.829), history of peptic ulcers (HR: 3.601, 95% CI: 1.226-2.829) or tumor (HR: 4.884, 95% CI: 1.226-2.829), and cardiac insufficiency (HR: 11.513, 95% CI: 7.282-18.202), renal insufficiency (HR: 2.010, 95% CI: 1.350-2.993), and prolonged activated partial thromboplastin time (HR: 4.639, 95% CI: 2.146-10.032) were independent risk factors for GIB 1 year after PCI. Based on these 7 factors, a nomogram and scoring system was established. The area under curve of risk score was 0.824 in the deviation cohort and 0.810 in the verification cohort. In both cohorts, the GIB score was significantly better than that of 3 classical bleeding scores (all P < .05).This score could well predict the risk of GIB within 1 year after PCI and could be used to guide antithrombotic strategies.