We describe a snub-nosed monkey that is new to science from the high altitudes of northeastern Kachin state, northeastern Myanmar, the Burmese snub-nosed monkey, Rhinopithecus strykeri sp. nov. Descriptions are based on a skin and skulls of four specimens obtained from local hunters. The new species is geographically isolated from other snub-nosed monkeys and separated from them by two major barriers—the Mekong and the Salween (Thanlwin) rivers. The species is chiefly diagnosed by its almost entirely blackish fur coloration with white fur only on ear tufts, chin beard, and perineal area, and its relatively long tail (140% of head and body length in the adult male). Preliminary surveys and interviews with hunters indicate that the new species is limited in distribution to the Maw River area, a small region of the Salween-N'mai Hka divide in northeastern Kachin state, northeastern Myanmar. The distribution area appears to cover about 270 km2, and the species may consist of only three groups with a total population of approximately 260–330 individuals. Our data on hunting pressure suggest that the species is Critically Endangered. Am. J. Primatol. 73:96–107, 2011. © 2010 Wiley-Liss, Inc.