Аннотация:The paper discusses the main stages of investigation into the dialectological situation in the South of Russia, with special attention being given to the studies of territories close to the Republic of Crimea. This paper presents findings from a field study of the Russian language functioning in an isolated area. We investigate speech of the people living in Greater Sevastopol to identify peculiar features in phonetics, word building, morphology and syntax. Our respondents are both natives and migrants from various regions. The regiolect of Sevastopol is analysed in terms of dialect bases and their correlation, time of migration. Our results show positive relationship between the respondents linguistic and biographic background. The speech of the respondents exhibits a high degree of similarity with the Russian literary language, and demonstrates features of the closely related Ukrainian language. The influence of Ukrainian is more pronounced at the phonetic level and less evident at the lexical level.