The article presents data on genetic variability in populations of two brown frog species: the moor frog Rana arvalis and the siberian wood frog R. amurensis, in Western Siberia, Russia. Persentage of polymorphic ISSR-PCR-bands in R. arvalis was 63-93 %, in R. amurensis - 90 %, genetic diversity indices were 0.18-0.20 and 0.31, respectively. The high level of genetic variability in the siberian wood frog is contrary to its low population size, restricted distribution in the study area and the boundary position of the population. Some ISSR-PCR-bands were species-specific, they can be used for fast genotyping and further population genetic studies of the siberian wood and the moor frog in their areas of cohabitation.