The Hainan black-crested gibbon Nomascus sp. cf. nasutus hainanus is on the verge of extinction. Following studies in the late 1980s and early 1990s only limited observations were made of the remaining population in the Bawangling National Nature Reserve on Hainan Island, China, and the most optimistic estimation of the population size was 23 individuals. To determine the present status of this gibbon, we surveyed the western part of the Reserve, from where the gibbons were previously known, using transects (November–December 2001), listening post (February–April 2002) and interviews with reserve staff (November–December 2001 and February–April 2002). Three groups of gibbons were sighted comprising at least 10–12 individuals including juveniles and infants. A fourth group, possibly comprising 2–7 individuals, was heard but not seen. Compared to an unpublished survey by reserve staff in 2000, the population appears to have decreased. Surveying of this gibbon population will continue, in particular to determine the composition of the one group that was heard but not seen and to carry out a survey of the eastern part of the Reserve to determine whether or not any gibbons survive there. The Forestry Bureau of Hainan is applying to the Central Government for an enlargement of the area of the reserve and more staff to help prevent illegal poaching and logging.