Objective: In Sweden complications after radical cystectomy have been reported to the nationwide population-based Swedish Cystectomy Registry since 2011. Here, validation of the reporting was assessed in two healthcare regions.Materials and methods: Complications were ascertained from patient records by a third party not involved in the care delivered to 429 randomly selected patients from 949 who had undergone radical cystectomy since 2011 in four hospitals. Without knowledge of the outcome in the primary registration, post-operative complications within 90 days post-operatively were assessed by an independent review of patient charts, and the results were compared with the primary reports in the Swedish Cystectomy Registry.Results: The third-party assessment identified post-operative complications in 310 patients (72%). Low-grade complications (Clavien-Dindo I-II) were noted in 110 (26%) of the patients in the primary registration, but increased to 182 (42%) in the validation (p?