The diversity of plant species belonging to the Poaceae family in Iran is very rich with about 500 known species. Many species of gall midges (Diptera: Cecidomyiidae) have a feeding relationship with plants of the Poaceae family. Despite the great species richness of Poaceae in Iran and the association between Cecidomyiidae/Poaceae, only 6 species of gall midges have been collected and identified from the plants of the Poaceae in Iran. In the present investigation related to the gall midge fauna of Iran, 3 genera namely, Calamomyia Gagn & eacute;, 1969, Epicalamus Sylv & eacute;n, 1998 and Mayetiola Kieffer, 1896 and 13 species namely, C. echinochloa Felt, 1916, Contarinia festucae Jones, 1940, C. floricola (Oettingen, 1927), C. lolii Metcalfe, 1933, Dasineura alopecuri (Reuter, 1895), E. phalaridis Sylv & eacute;n, 1998, Lasioptera arundinis Schiner, 1854, L. calamagrostidis R & uuml;bsaamen, 1893, L. donacis Coutin, 2001, Mayetiola poae (Bosc, 1817), Stenodiplosis sorghicola (Coquillett, 1899), S. geniculati (Reuter, 1895) and S. panici Plotnikov 1926 are reported for the first time from the country. The adult specimens were obtained by rearing from their larvae on 13 genera and 13 species of Poaceae. The genus Calamomyia Gagn & eacute; 1969, which is distributed in the Nearctic region, is reported for the first time from the Palearctic region.