A list of 55 species of Diptera from families Tanypezidae (1 species), Megamerinidae (1), Acroceridae (1), Psilidae (5), Lonchaeidae (8), Strongylophthalmyiidae (1), Ephydridae (21) Scathophagidae (17 species) collected in the Republic of Mordovia is given. Of them Protearomyia withersi MacGowan, 2014 and Lonchaea baechlii MacGowan, 2016 are recorded from Russia for the first time. Five species, namely Megamerina dolium Fabricius, 1805, Lonchaea carpathica Kovalev, 1974, Ephydra scholtzi Becker, 1896, Strongylophthalmyia pictipes Frey, 1935 and Chamaepsila bicolor (Meigen, 1826), are new for Central part of European Russia. The families Acroceridae, Megamerinidae, Psilidae, Tanypezidae and Strongylophthalmyiidae as well as 53 species are recorded from the Republic of Mordovia for the first time.