The article provides an overview of Lithuanian dialects and their classification. Two of them were of particular significance: the system devised by Baranauskas in 1898 and the classification of Jaunius prepared in 1890-1911, whose principles were used by Salys to create the first scientific classification of Lithuanian dialects in 1933, when the methods of historic comparative linguistics were applied. The rise of structuralism gave the impetus for phonological classification in the second half of the 20th century. The system designed by Zinkevičius and Girdenis in 1966 is still considered to be the main dialect classification of Lithuanian dialects – it is based on certain phonetic (phonological) criteria, but no other criteria (lexical, morphological, or syntactical) have so far been used as the basis for dialect classifying. The dialect variation of the Lithuanian language in the early 21st century is reflected in the new dialect derivations – regiolects and geolects (2014).