The Mirasol PRT System (Gambro BCT, Lakewood, CO) for platelets and plasma uses riboflavin and UV light to reduce pathogens and inactivate white blood cells in donated blood products. An extensive toxicology program, developed in accordance with International Organisation for Standardisation (ISO) 10993 guidelines, was performed for the Mirasol PRT system. Test and control articles for most of the reported studies were treated (test) or untreated (control) blood products. For some studies, pure lumichrome (the major photoproduct of riboflavin) or photolyzed riboflavin solution was used. Systemic toxicity was evaluated with in vivo animal studies in the acute and subchronic settings. Developmental toxicity was evaluated with an in vivo animal study. Genotoxicity and neoantigenicity were evaluated with in vitro and in vivo tests. Hemocompatibility and cytotoxicity were assessed with standard, in vitro assays. The pharmacokinteics, excretion, and tissue distribution of (14)C-riboflavin and its photoproducts was evaluated with an in vivo animal study. The possible presence of leachable or extractable compounds (from the disposable set) was evaluated with novel assays for measuring these compounds in blood. No treatment-related toxicity was observed in any of the studies.