The article deals with essential aspects of the sociolinguistic situation and, partly, the phonological and grammatical systems of Czech immigrants’ dialects spoken in Russia. One of the examined dialects is used in two villages near Novorossiysk and Anapa in the Northern Caucasus, and the other in the Middle Irtysh area of the Omsk Region. The dialects appeared as a result of different waves of Czech rural migration at the end of the 1860s and the start of the twentieth century. The primary purpose of this research is to describe the process of formation of the two dialects, their functioning within the community and their contact with the languages used outside, as well as external factors that contributed first to their survival and then to the breach of dialect transmission in families since the 1970s. In the process, the article outlines the main linguistic features of the two dialects, focusing on those that indicate the dialects’ origin and those that have been affected by the languages of their surroundings. The corpus of interviews with speakers of Czech heritage in Russia used in this article likely represents the largest data collection to date.