The trade in illegally captured wildlife is an ongoing, and in many cases increasing, threat to conservation. Primates in particular make appealing pets when young but are frequently rejected or abandoned upon reaching sexual maturity. The trade in gibbons, for example, is a lucra- tive market, with infant gibbons worth between US $10 and 500 on the international black market. This represents a large sum of money for the average family, even allowing for the cost of a bullet and gun. Trade in highly endangered primates continues despite the existence of legislation against hunt- ing throughout most primate ranges. The situation is further exacerbated by logging and the perma- nent conversion of forests to plantations which results in the loss and fragmentation of habitat. Despite this rather bleak outlook, conservation NGOs working with local communities are having an effect. The merits and challenges of rehabilitation and reintroduction of primates are discussed using gibbons as a case study. Data collected at the Kalaweit Gibbon Rehabilitation Project, Central Kali- mantan, Indonesia, are used to highlight the many considerations behind a successful rehabilitation and reintroduction project, the importance of detailed behavioural data and the keys to success. Finally, the 'rehabilitation debate' is discussed, i.e. are rehabilitation and reintroduction projects good tools for habitat protection and the conservation of a species?