We have analyzed information about the raccoon (Procyon lotor) introduction and acclimatization progress in the former Soviet Union and Middle Europe with respect of the threat of invasion of this alien species to ecosystems of Lithuania. Currently, Lithuania is situated between two naturalized raccoon populations that could be potential sources of invaders. First population situates in Pripyat River Valley, Belarus (appr. 250 km from the Lithuanian border). Here, the number of raccoons reached 700-800 animals but further range expansion was not observed. Different population trends have been observed in Germany and Poland, where raccoons are expanding their distribution range. We believe that the different tendencies in dynamics of the Belarusian and the German-Polish raccoon populations are probably reasoned by the differences in the environmental structure. The two raccoon populations may be differently adapted to anthropogenic environmental changes. For this reason, a greater threat for Lithuania is the raccoon invasion from Poland than from Belarus. Third possible threat of the raccoon naturalization is keeping raccoons as pets and the consequent deliberate release to the wild after they become a nuisance (or animals escape from captivity). We analyzed the known cases of raccoon observation in Lithuania in the last five years and concluded that they all likely originate from captivity. We also highligth a great public interest to the raccoon as a pet. In Lithuania, the trade on raccoons is illegal. However, the WEB stores are full of advertisements suggesting to purchase these animals in neighboring countries. On the other hand, a low probability exists that such a released (escaped) solitary individual(s) could find a partner and establish a local viable population.