A total of 34 species belonging to 11 families and 21 genera in the Order Mestostigmata are reported from the Korean Peninsula, of which 20/34 species are new for the fauna of the Korean Peninsula (Lasioseius furcisetus Athias-Henriot, 1959, Cheiroseius nepalensis Evans & Hyatt, 1960, Cheiroseius curtipes (Halbert, 1923), Hypoaspis imitatus Reitblat, 1963, Hypoaspis presternalis Willmann, 1949, Hypoaspis kargi Costa, 1968, Pseudoparasitus placentulus (Berlese, 1887), Gamasiphis novipulchellus Ma & Yin, 1998, Parholaspulus bregetovaae Alexandrov, 1965, Parholaspulus paradichaetes Petrova, 1967, Neparholaspis arcuatus Petrova, 1977, Neparholaspus simplex Evans, 1956, Parholaspulus excentricus Petrova, 1967, Gamasholapis asiaticus Petrova, 1967, Veigaia carpillaris Tseng, 1994, Veigaia anmashanensis Tseng, 1994, Leptogamasus bicorniger Witalinski, 1977, Neogamasus insignis (Holzman, 1969), Iphidinychus kakumeiensis Hiramatsu & Hirschmann, 1992, Trigonuropoda sanguinea Hirschmann & Hiramatsu, 1977). A total of 19 of the previously unreported species were collected in soil samples from the Democratic People's Republic of Korea (DPRK), while 13 species were collected from soil samples from the Republic of Korea (ROK). Only two species were found in both the DPRK and the ROK. Illustrations and short descriptions for previously unreported species provided.