Bornean gibbons Hylobates muelleri are protected by law in Sarawak, but their habitat is being destroyed, they are illegally hunted, and they are captured for the pet trade. The Wildlife Rehabilitation Centre at Semengok Forest Reserve, which is run by the National Parks and Wildlife Office of the Sarawak Forest Department, receives confiscated gibbons and those surrendered by the general public. Between October 1976 and June 1988,122 gibbons were received and 87 were subsequently released. The rate of survival was unknown until the author organized a survey of the forest at Semengok in 1988. It revealed that about 90 per cent of the gibbons did not survive long after release. The author discusses the reasons for this high mortality rate, the shortcomings of rehabilitation as a conservation tool, the problems facing the conservation authorities, and options for dealing with confiscated primates.