Historically the black crested gibbon (Nomascus concolor,N. sp. Cf. nasutus) has ever been distributed widely in southern and southeastern Yunnan. A series of field surveys and interviews were conducted with local people, from July 2003 to December 2004 to assess the conservation status of the gibbons in southeast Yunnan. Results demonstrated that the eastern black crested gibbon (N. sp. Cf. nasutus) and the western black crested gibbon (N. concolor) disappeared in the Niuluohe Nature Reserve of Jiangcheng County, Gulinqing Nature Reserve of Maguan County, Laojunshan Nature Reserve of Malipo County and probably in Daweishan Nature Reserve of Pingbian County. Less than 25 individuals of 4-7 groups were found in isolated habitats in Bajiaohe (2 groups), Xilongshan (1-2 groups) nature reserves located in Jingping County, and Huanglianshan (1-3 groups) nature reserve in Luchun County. Great loss of habitats and heavy hunting caused distributions reduction and population decline.