The worm burden distribution of three trematodes (Diplodiscus japonicus, Glypthelmins rugocaudata, Gorgodera japonica) and three nematodes (Cosmocerca japonica, Rhabdias nipponica, Oswaldocruzia socialis) were examined in naturally infected populations of anurans from Korea. All parasite species had over-dispersed distributions which were well described by the negative binomial probability model. The values of k of nematodes were greater than those of trematodes. From the values of k of R. nipponica (1.04) and O. socialis (1.47), it could be conferenced that an equilibrium between host and parasite populations was reached resulting from the regulation of both populations.