A karyotype analysis of the chromosome of Neodiplostomum seoulense, one of causative agents of human intestinal trematodiasis, was done from the gonad tissue by the squashing method. The chromosome number was n = 10 and 2n = 20. Chromosome length was 1.30-4.0 microns. Chromosome pairs in the complement consisted of two pairs of metacentric, five pairs of submetacentrics/subtelocentric and three pairs of telocentric chromosomes. These data were comparable with those of other intestinal trematodes.