To clarify the species of genus Deutzia (Saxifragaceae, s. l.) in Korea, the taxonomic description was undertaken and interspecific relationships was discussed based on the external morphology with the light and scanning electron microscopes and the distributional pattern with specimens deposited in the herbaria. The presence or absence, number of rays, position and frequency of the stellate trichome, inflorescence and the morphology and venation pattern of petal were approved as the good characters to classify the Korean Deutzias. Although 17 kinds of Deutzia were reported in Korea hitherto, 9 kinds were excluded owing to the taxonomic treatment based on the comparative external morphology and the distributional uncertainty. Thus genus Deutzia in Korea could be rearranged as 2 sections, 3 subsection, 7 species and 1 variety. Among them, 4 species were considered as the endemic species in Korea.