Allozyme study in Korean cultivated radish, Raphanus sativus L. var. hortensis Backer f. acanthiformis Makino, was conducted to estimate the levels and distribution of genetic variation among populations using starch gel electrophoresis. Populations of cultivated radish show moderate levels of allozyme variation; the mean percentage of polymorphic loci was 39.4%, mean number of alleles per locus was 1.52, and mean expected heterozygosity was 0.079. It is probable that a combination of outcrossing breeding system, high fecundity, and cultivated status may in part be explanatory factors contributing a moderate level of genetic diversity within populations. An overall slight deficiency of heterozygotes relative to Hardy-Weinberg expectations (mean FIS = 0.076) indicates that consanguineous mating occur within cultivated radish populations. Of the total genetic variation found in cultivated radish populations examined, only 7% is due to differences among populations (mean GST=0.073). It is supposed that the cultivated status of radish may influence the considerably low population differentiation. In addition, seed dispersal by humans leads to enhanced levels of gene flow and decreased population divergence in Korean cultivated radish.