Molecular-genetic analysis of green frogs (67 individuals of Pelophylax ridibundus and 63 ones of hybridogenic P. esculentus) from Mari El Republic (15 localities) and the Kirov Region (one locality) was performed by two (mitochondrial and nuclear) markers. Some part of the material (66 individuals) was studied by means of DNA flow cytometry. It is shown that in the green frogs living in the northern Middle Volga region, the genetic markers specific for the «western» (the Central European P. ridibundus) form are predominant.