Three hydrophilid species [Agraphydrus ishiharai (Matsui), Crenitis primorica Hebauer, and Laccobius formosus Gentili] are identified for the first time in Korea. We also found that Laccobius fragilis Nakane previously recorded in Korea was an incorrect identification of L. formosus. Habitus photographs, diagnoses, and diagnostic characters with illustrations of the species are provided.