The available data on the present distribution of Cepaea nemoralis in Ukraine, Belarus and the European part of Russia, the history and possible ways of penetration of this species into various parts of Eastern Europe, as well as the colour and banding polymorphism of its shells are analyzed. It has been suggested that the process of rapid spreading of C. nemoralis in the three compared Eastern European countries began at approximately the same time (late 20th – early 21st centuries) and that it may be caused by active and practically uncontrolled importation of seedlings from other European countries, as well as by global climate change, which can contribute to better survival of snails outside their natural range. Despite the possible initial limitation of the phenotypic and genetic diversity associated with the accidental transfer of a limited number of individuals, in the Eastern European colonies, in general, a fairly large variety of the inherited traits of the shell colouration remains. This concerns, first of all, the polymorphism in the shell ground colour (yellow, pink, less often brown) and the main variants of the shell banding (unbanded, mid-banded, five-banded, less often three-banded).