Morphological features of the two Korean Acrosorium species, A. flabellatum Yamada and A. venulosum (Zanardini) Kylin (Delesseriaceae, Rhodophyta) are described based on specimens collected from several localities along the coasts of Korea. Acrosorium flabellatum is easily distinguished from other Acrosorium species in lacking rhizoids in branchlets for attachment to substratum. The flabellate branching is also characteristic for this species. By contrast, Acrosorium venulosum is distinct from others in having the unique hooked branchlets. Taxonomic features found in the Korean Acrosorium species are compared, and a key to the species is provided based on this and previous data.