Light and scanning electron microscopic observations on the radular teeth of six well known species of Korean freshwater pulmonates such as Radix auricularia coreana and Austropeplea olluia in Lymnaeidae, Physa (Physella) acuta in Physidae, and Gyraulus convexiusculus, Hippeutis cantori and Segmentina hemisphaerula in Planorbidae were undertaken. The snails belonging to Planorbidae have bilaterally symmetrical bicuspid central teeth. In Lymnaeidae R. auricularia coreana has an asymmetrical bicuspid central tooth while A. ollula has a monocuspid one. P. (Physella) acuta in Physidae has a multicuspid central tooth. The majority of the species have tricuspid lateral teeth, but P. (Physella) acuta has comb-like lateral teeth. The majority of them have comb-like or rake-like marginal teeth while H. cantori has scoop-like marginal teeth. The numbers of radular teeth per horizontal row including the central, lateral and marginal teeth are 61 in R. auricularia coreana, 65 in A. ollula, 173 in P. (Physella) acuta, 35 in G. convexiusculus, 51 in H. cantori. and 43 in S. hemisphaerula. The arrangement pattern of the radular teeth in P. (Physella) acuta is based on ∧ frame which is quite different from other species. S. hemisphaerula and H. cantori do not have distinct transitional teeth between the lateral and marginal teeth unlikely to the other species.