The harvesting of wild animals and plants for international trade affects thousands of species, and compounds ongoing extinction threats such as habitat loss and climate change (1-4). The loss of over-exploited species can result in cascading effects that reduce overall ecosystem functioning (4-5). The primary international framework for preventing the loss of species due to international wildlife trade is the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Given that CITES aims to be as scientifically based as possible (7), we analyzed how quickly species that are identified by the International Union for the Conservation of Nature (IUCN) “Red List” as being threatened from trade are subsequently protected under CITES. The Red List represents an authoritative body of scientific knowledge regarding extinction risks. We find that in nearly two-thirds of the cases the CITES process of regulating trade in threatened species lags considerably behind the IUCN Red List identification of species in need of protection from trade. Such delay in the application of scientific knowledge to policy formulation could result in the extinction of species. With signatories to CITES set to gather in June 2019 to determine which additional species merit protection and which no longer require it, we suggest opportunities to improve this process.