Proboscis monkey (Nasalis larvatus) is an endemic primate species of Borneo that is protected in Indonesia and is endangered. This species could be found in Mount Kentawan, Loksado. The objective of the research was to count the density of proboscis monkey. The monkeys were counted by concentration count technique in 4 (2,000 x 50) m paths. The proboscis monkey density was 55 ind/km2. Keywords: density, path, population, proboscis monkey