Safety profiles of abiraterone and enzalutamide mainly rely on phase III clinical trials. Our objective was to estimate the incidence rate ratio (IRR) for certain adverse events leading in real life to hospitalization (atrial fibrillation, acute heart failure, ischemic heart disease, acute kidney injury (AKI), ischemic stroke, torsade de pointe/QT interval prolongation, hepatitis, and seizure), comparing abiraterone to enzalutamide.