Introduction. The article is a continuation of the author’s publication in the journal “Vestnik of the Mari State University”. It analyzes the classification of dialects and patois of the Mari language by the Hungarian scientist G. Bereczki. The principles are considered, the main language parameters, dialect differences at the phonetic, morphological and lexical levels are determined. Despite the fact that the monograph of the scientist was published in 1994, nevertheless, the basic principles and complete characteristics of dialects and patois are offered to the Mari scientific community for the first time. The purpose of the study is to analyze and systematize the main provisions and principles in the division of the Mari dialects by G. Bereczski. Materials and methods. A monograph and articles by G. Bereczki on the dialects and patois of the Mari language served as research material. The work uses mainly a descriptive method. Research results, discussions. As a basis for the division of Mari dialects and patois, G. Bereczki takes the following features characteristic of the entire Mari language: vocalism of the first syllable, plural indicator, individual case suffixes in the declension system, differences in the conjugation system of the Mari verb, preservation of Ural derivational suffixes in a particular dialect, lexical indicators, etc. If necessary, he offers a historical excursion, draws on ethnographic data, elements of the material and spiritual culture of the Mari people. G. Bereczki uses the rich linguistic material of E. Beke’s “Dialect Dictionary of the Mari Language,” as well as his own notes made during dialectological expeditions with different groups of Mari. In the Mari language, he identifies Western and Eastern dialects with their patois and sub-dialects. Conclusion. The division of dialects of the Mari language, proposed by G. Bereczki, deserves close attention from Mari linguists. It deserves recognition as a scientific classification of dialects and patois in Mari linguistics.