Sanctuaries and rehabilitation centres must strive to demonstrate not only a welfare benefit to individuals but also a measurable contribution to the conservation of species. We will discuss how to carry out the rescue, rehabilitation and reintroduction of gibbons and the rationale behind the process, based on what is known and is being learnt about rehabilitating these species. This document is focused on guidelines for in situ rescue, rehabilitation and release, to account for the limitations in access to resources in developing countries. Some of the suggestions mentioned here may not be practical for all rehabilitation centres. This essay is not designed to be a complete guide to the rehabilitation and welfare of gibbons but should be used as a template. It is intended to be the beginnings of a living document and is formed from personal observations and, where noted, from procedures being used at the Kalaweit Gibbon Rehabilitation Project in Kalimantan, Indonesia, from the Javan Gibbon Centre in Java, Indonesia, and from an extensive search of the literature. Standardizing procedures across all in situ rehabilitation centres will help to prevent the repetition of mistakes and ensure that all centres follow similar medical and husbandry procedures for these threatened species.