Dipteran insects constitute 51 % among arthropods of the Rovno Amber. There are 99 species and 23 genera of the Diptera described from the Rovno Amber; however, to date only 32 species are shared with the Baltic Amber fauna, including two species that are treated in this paper. Triphleba schulmanae Brown, 2003 (Phoridae), originally described from the Baltic Amber, is recorded in the Rovno Amber for the first time and its amended description is supplied. Genus Prosphyracephala Hennig, 1965 (Diopsidae), earlier known from the Baltic and Saxonian ambers, the Upper Eocene of Ruby River (Montana, USA) and the Lower Oligocene of Céreste (France), is recorded in the Rovno Amber for the first time. Prosphyracephala aff. succini (Loew, 1873) is the first diopsid record from Ukraine. A second specimen of Prosphyracephala kerneggeri Kotrba, 2009 is found in the Baltic amber; the complete wing venation is described for the first time for this species. Vast majority of the Old World Diopsidae are strictly thermophilous. In fact, all of them but the five species of brevicornis group of Sphyracephala Say (three Palearctic and two Nearctic ones) frequent tropic and the warmest subtropic areas, however the thermophilous Diopsidae are known in the New World neither in past nor in contemporary fauna.