Mosiro is an extinct Nilo-Saharan language spoken in the Arusha Region of Tanzania. It was the primary language of the hunter-gatherer Mosiro, Mediak and Kisankasa. It is classified as a variety of Ogiek by Rottland (1982) and Sommer (1992), but is assimilated to Nandi. Like other hunter-gatherers in the area, the Mosiro are called derogatory Dorobo (Ndorobo). Ethnologue lists three "Ndorobo" languages in the area besides Okiek: Mosiro, Mediak and Kisankasa. However, the only source for the latter two reported that they were indistinguishable from Mosiro.