OBJECTIVES: Post-marketing requirements (PMRs) include studies and clinical trials that sponsors are requiredto conduct under one or more statutes or regulations. The objective of this research is to identify which therapeutic areas, and within these areas, which therapeutic indications have been subjected to the highest number of PMRs from the Food and Drug Administration (FDA, USA) and the European Medicines Agency (EMA, EU). METHODS: The Post-Marketing Requirements Database was used to explore requirements for post-approval studies published on the websites of the FDA and the EMA since 2005. The search was performed on January 2, 2013. RESULTS: The therapeutic area for which the EMA required the highest number of studies was “factors influencing health status and contact with health services” (n = 36) for the indication “prophylaxis of influenza in a pandemic situation” (n = 36). Within this indication, ten different products were concerned with Pandemrix and Cepalvan being the products with the highest number of studies requested (n = 6 for each product). In comparison, the FDA had requested only 27 studies for the same therapeutic area, and neither Pandemrix nor Cepalvan were approved in the USA. The area for which the FDA requested the highest number of studies was “endocrine, nutritional and metabolic diseases” (n = 80), and within this area, the more populated indication was “diabetes mellitus”(n = 41). Within this indication, Onglyza, Byetta and Victoza were the products with the highest number of studies requested (n = 4, 5, and 6 respectively). In comparison, the EMA had requested only 14 studies for the same area. Onglyza, Byetta and Victoza were approved in Europe but not subjected to PMRs. CONCLUSIONS: This brief review showed discrepancies in PMRs between the FDA and the EMA. More research is needed to explain these differences.