Data are presented on the changes in distribution and abundance of the Mongolian saiga Saiga tatarica mongolica in the last few decades, based on an analysis of the literature and the authors' field observations. The subspecies has suffered a considerable decline in its range because of hunting and competition with domesticated stock. In 1997 a survey was made of almost all the known range, which consists of two disjunct areas and covers a total of 2200 sq km. A total of 609 animals was recorded and analysis of the census results suggests that c. 1300 saiga remain in total. The authors recommend strengthening the nature reserve established in 1993 in the Shargyn Gobi, and creating several sanctuaries outside this area, where Mongolian saiga from the main remaining population could be reintroduced. These measures would enhance prospects for the survival of this endemic subspecies of the semideserts of western Mongolia.