The genuine mahoganies (Swietenia spp., Meliaceae) are the most valuable timber species in Latin America. Only one species, bigleaf mahogany S. macrophylla, is still traded. Because of concerns regarding logging it is regulated under Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). We analyze implementation of CITES regulations by the USA, which is the major importer, comparing CITES statistics with data from US Customs to determine if shipments entering the USA have proper CITES documentation. Based on summary data for 1997–1999 (the most recent available), US Customs reports substantially more mahogany imports than CITES, although >90% of imports were accompanied by the proper CITES documents. The discrepancies resulted from (1) changes in shipment volume made after permits were issued, (2) data transcription and unit conversion errors, (3) mistaken inclusion of other species in Customs data, and (4) imports that might or might not have been accompanied by the appropriate CITES documents. The analysis demonstrates that the USA is properly implementing CITES requirements. However, mahogany may be smuggled under different species names. Furthermore, the numerous credible reports of widespread illegal mahogany logging suggest that a substantial proportion of US imports might have been obtained in a manner inconsistent with the domestic laws of the exporting countries. Thus illegally obtained mahogany might have been ‘legalized’ through the CITES process, with Appendix III providing a veneer of legality to what is otherwise illegal wood.