The crane fly family Cylindrotomidae is newly recorded for Mongolia. Four species, Cylindrotoma distinctissima (Meigen, 1818), C. nigriventris Loew, 1849, Diogma glabrata (Meigen, 1818), Phalacrocera replicata (Linnaeus, 1758) are first recorded in Mongolia from sampling during 2002–2006. An illustrated key to identify these species, and the regional C. japonica Alexander, is presented. The two subspecies of Diogma glabrata (Meigen, 1818), D. g. megacauda Alexander 1931 and the nominotypical subspecies, are not supported as distinct.