Serological and biochemical polymorphisms in marker genes of the AB0, MN, RH, FY, HP, TF, ACP1, PGM1, ESD, and GLO1 systems were studied in the combined sample of 369 individuals of Chuvash ethnicity from Morgaushskii, Mariinsko-Posadskii and Yadrinskii districts of the Chuvash Republic. We have compared our results with the data obtained in previous studies by other authors. A linear relationship has been established between genetic and geographical distances by examining 11 ethnoterritorial groups in Northeastern Europe and Western Siberia.