Acute coronary syndromes (ACS) continue to pose significant challenges for clinical practitioners, particularly regarding the prediction of mid- to long-term outcomes. This study aims to investigate the impact of in-hospital bleeding (IHB) at 1-year follow-up in patients admitted for ACS. Data from 23,270 patients enrolled in the international PRAISE registry and discharged after ACS were analyzed. A total of 1060 patients experienced IHB, whereas 18,765 did not; 3445 were excluded because of missing data. The primary endpoint was all-cause mortality at 1 year. Secondary endpoints included major bleeding, reinfarction, and composite endpoints at 1 year. Patients with IHB were older, more frequently female, and had a higher prevalence of cardiovascular risk factors (all P < 0.05). At discharge, IHB patients were less likely to receive optimal medical therapy. At the 1-year follow-up, all-cause mortality, major bleeding, and reinfarction were significantly higher in the IHB group (all P s < 0.001). Bivariate analysis showed a strong association between IHB and all the outcomes of interest (all odds ratios >1; all P s < 0.001). These associations remained significant even after adjusting for several covariates, except for reinfarction (odds ratio 1.3; 95% confidence interval 0.9-2.11; P = 0.149). Age, female sex, hypertension, and peripheral artery disease were found to be independent predictors of IHB, whereas drug-eluting stent implantation, radial access, and left ventricular ejection fraction were identified as protective factors. IHB is a hallmark of frailty in patients with ACS; therefore, greater attention should be given during follow-up to patients experiencing this condition.