A cross-sectional study assessed compliance with legislation and recommendations to publish protocols and results of post-authorisation studies registered by the European Medicines Agency (EMA) based on data from February 2024. 2300 studies (1484 completed, 816 ongoing) were analyzed for protocol availability and 1482 completed studies for outcome availability. Protocols were publicly available for 1370 (59.6%) of the 2300 studies. For risk management plan (RMP) studies, protocols were available for 76 (68%) of 112 EU RMP category 1 studies, 21 (64%) of 33 category 2, 419 (67%) of 625 category 3 and only 3 (0.2%) of 1292 non-RMP studies. Results of completed studies were available for 1084 (73%) of 1482 studies, including 61 (90%) of 68 category 1, 17 (90%) of 19 category 2, 304 (75.8%) of 401 category 3, and 54 (64%) of 83 non-RMPs. Adherence was poor, especially in studies outside the RMP where there is no legal obligation. Assessing the availability of data in the EMA catalog is feasible and promotes research transparency.