PURPOSE: To perform a systematic review (SR) to examine the application of classification systems (CS) used to report intraoperative adverse events (iAEs) in urological surgery and to evaluate the crude incidence and type of iAEs. MATERIALS AND METHODS: This review was published via PROSPERO (CRD42024549954) and conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). MEDLINE, Embase, and the Cochrane CENTRAL were searched using a predefined PICO framework: (P) patients with benign and malignant urological diseases, (I) all types of urological surgery, (C) none/any, (O) intraoperative complications classified with grading systems. Retrospective and prospective studies published between January 2019 and June 2024 were included. RESULTS: The search yielded 1,570 abstracts, 1,043 full-text articles were assessed for eligibility, of which 325 studies reported iAEs (54 used iAE-CS, 64 used Clavien-Dindo Classification and 207 used free-text descriptions). Of the 54 studies (15,298 patients) that used an iAE-CS, the three most used systems were the EAUiaiC (54%), SATAVA (26%), and the modified SATAVA (7%). The overall incidence of iAE was 14% (2,153/15,225 patients). On a study level, the crude incidence of iAE was between 0 and 100% (median 7%, IQR: 3-13%). The misapplication of the Clavien-Dindo system to describe iAEs was high (n = 64 studies). CONCLUSIONS: The use of iAE-CS is scarce, and there is a lack of universal consensus on a CS to describe iAEs. iAE are poorly reported in urological studies. Urologists should report all perioperative complications to improve transparency and surgical and hospital processes.