A total of 1003 two-winged species that belong to 58 families have been reported from the Rila Mts. The Tachinidae (162 species or 16.1%) and Syrphidae (149 species or 14.8%) are the most numerous. The great number of species (736 species -- 73.4%) has been found in the beech forest belt. The established species belong to 84 areographical categories. The dipterous fauna can be divided into two main groups: 1) species with Mediterranean type of distribution (48 species or 4.8%): more thermophilic and distributed mainly in the southern parts of the Palaearctic. Three species of southern type, distributed in the Palaearctic and beyond it, can be formally related to this group as well; 2) species with Palaearctic and Eurosiberian type of distribution (955 species or 95.2%): more cold-resistant and widely distributed in the Palaearctic. Two hundred fifty-five species of northern type, distributed in the Palaearctic and beyond it, can be formally related to this group as well. The Holomediterranean (eight species or 0.8%) and South European (seven species or 0.7%) forms are best represented in the first group. The European (183 species or 18.2%), Holarctic (124 species or 12.4%), Holoeurosiberian (82 species or 8.2%) and Transpalaearctic (78 species or 7.8%) taxa prevail in the second group. The endemic species are 12 (1.2%). The zoogeographical character of the fauna is determined by the second group. The distribution of the separate categories in the vegetation belts of the Rila Mts. is presented.