This report presents an assessment of the trade in gibbons and orang-utans in Sumatra, Indonesia, including the islands off Sumatra’s west coast (most notably, the Mentawai Islands). TRAFFIC’s overall goal for this study was to create an overview on all aspects of the trade and ‘uses’ of these species throughout Sumatra, and trade connections to other parts of Indonesia, and present it to the relevant authorities as a report with recommendations for action to improve conservation efforts for these primates.