Key PointsQuestionWas the Russian invasion of Ukraine in 2022 associated with changes in registration data for ongoing clinical trials with Ukrainian sites?FindingsIn this cross-sectional study including 888 trials conducted only in Ukraine or within multiple countries, changes to the registered data in the ClinicalTrials.gov registry 1 year after the beginning of the Russian invasion were mostly similar to those posted 1 year before the war. In trials conducted solely in Ukraine, the number of changes to the trial records was similar before and after the start of the war, and similar to registered trials from Estonia and Slovakia.MeaningThese findings suggest that trial sponsors may have not been providing war-related changes in trial conduct in Ukraine in the largest public trial registry, expected to present accurate and timely information on clinical trials.