This work is devoted to the study of onomatopoeic paired words of the languages of the central zone of the Volga-Kama language union – Chuvash and Mari. These languages belong to different families (Altai and Uralic), however, for many centuries they have been in close relations, as a result of which they were subjected to significant contamination. The purpose of this work is to establish general and particular parameters of paired words in the languages being compared. The material for the study was the Chuvash and Mari onomatopoeic words, phonetically close to each other. The conclusions of the work are based on the methods of comparative linguistics. On the basis of academic dictionaries, the author establishes a common layer of onomatopoeic paired words of the Chuvash and Mari languages. Studies have shown that, in a derivatological sense, paired words in both languages are built on the basis of the same model and represent onomatopoeia with an incomplete divergent reduplicative component in the final part of the word. At the same time, pairs practically do not reveal semantic convergences. It seems that the discovered feature of phonetically consonant paired words can be explained only by drawing on the genetic differences of languages that are implicitly preserved to the present and only make themselves felt with special scientific analysis.