The Convention on International Trade in Endangered Species (CITES) was conceived in the spirit of cooperation, with the aim of ensuring that the international trade in wild animals and plants, including all parts and derivatives, did not threaten their survival. However, concerns have been raised by scientists that CITES hinders the cross-border movement of scientific specimens. To our knowledge, no empirical analysis has been undertaken to demonstrate the existence of this effect. We test for a CITES effect on the collection record of orchids from Brazil and Costa Rica using the collection records of bromeliads, which are not covered by CITES, as a control. Highly significant effects are found in both countries.