The genetic polymorphism of placental glucose dehydrogenase (GDH) was investigated in 300 Korean placentae using horizontal starch gel electrophoresis. The allele frequencies for GDH¹, GDH² and GDH³ were 0.537, 0.440 and 0.005, respectively, which were similar to those in Japanese. We also observed an anodal allele which was similar to the GDH ⁴ originally reported in Chinese populations at a low frequency of 0.015. An additional new cathodal allele (named GDH ⁶) was observed in the present study with a very low frequency of 0.003.