Functional continuity among and within these areas with regard to the white-headed langur��s genetic connectivity has not been assessed, and the extents of individual migration and gene flow at various spatial scales remain unknown. Little is known about the species�� historical distribution and population size before the 1980s. The total distribution range for the species shrank by almost 80% Oxethazaine during the last two decades of the 20th century, along with extirpation of local populations in small habitat patches. One study MSDC-0160 reported nearly 60% population size reduction in Fusui area, where the largest extant population resides, from 1987 to 1997. Other distribution areas were likely to have experienced population declines during the same period of time. Habitat destruction and fragmentation by human development and poaching were possibly the main reasons for severe population decline during this period of time. Genetic data on the white-headed langur are very limited, and large-scale genetic studies have been lacking. One study found very low genetic diversity in the species in comparison with a closely related species, using mitochondrial DNA sequences from 54fecal samples. No data on population structure or genetic differentiation are yet available in the species. Appropriate conservation strategies demand accurate evaluation of the present and past population genetic parameters. In this study, we collected fecal samples noninvasively from 37% of all known social groups across the two main distribution areas, FS and Chongzuo, and analyzed haplotypic variation at the mtDNA control region. Our main aims were: to assess genetic diversity in the local and total populations, to investigate population structure and genetic differentiation among and within the local populations, to infer population demographic history, and to make management recommendations for conservation of the species�� genetic variation. By direct sequencing of PCR products, we found that all samples amplified a single sequence except samples of one social group from FS-BZ, which yielded two sequences differing at one site. This was most likely to represent a case of mitochondrial heteroplasmy, where more than one mitochondrial genome is present in an organism and can co-transmit.