From February 1988 though June 1990, 475 adult long-tailed macaques (Macaca fascicularis) were released on Tinjil Island to establish a breeding program that will provide monkeys for biomedical research while contributing to Indonesia's primate conservation efforts. A survey was conducted during the summer of 1990 to assess the status of the island's population. Basic demographic data were consistent with those from other field studies of long-tailed macaques, and estimates of reproductivity suggest a successful breeding program. The facility established on Tinjil Island should serve as a useful model for future primate resource and conservation programs. © 1993 Wiley-Liss, Inc.