The paper discusses the results of our study of the variability of some morphometric and reproductive characteristics in the common brown frog, Rana temporaria, from two populations of the Moscow city. The first population exists in isolation in the Timiryazev Forest Park, for a long time surrounded by districts with multi-storey buildings. The second population is located on the territory with mainly rural buildings (the settlement Kokoshkino), recently annexed to Moscow. The size and reproductive parameters in frogs from these two localities were compared.