Of the 16 genera of the subfamily Diplazontinae occurring in the Eastern Palearctic region, 11 genera are recognized from South Korea. Specifically, four genera (Campocraspedon Uchida, Diplazon Nees, Syrphoctonus Förster and Woldstedtius Carlson) are previously recognized from South Korea, whereas the other seven genera are recorded from this country for the first time. A key to the 16 genera of Diplazontinae occurring in the Eastern Palearctic region is provided. Six genera of Korean Diplazontinae (Bioblapsis Förster, Campocraspedon Uchida, Eurytyloides Nakanishi, Phthorima Förster, Promethes Förster and Sussaba Cameron) are reviewed here. Species of these genera rarely occur in the Eastern Palearctic region with small numbers of collected samples (excluding genus Sussaba). Here we provide diagnosis for seven species of Diplazontinae and one new species, Eurytyloides koreanus Balueva and Lee sp. nov., has been described.