It is for the first time for the Omsk region that the synopsis of alien vascular plants, including 252 species (subspecies) from 49 families is presented. For each species the time of occurrence (and the first record if available) and spread in the region are indicated. The largest number of species belongs to families Asteraceae, Brassicaceae, Poaceae, Chenopodiaceae, Fabaceae, Rosaceae, Lamiaceae and Boraginaceae. According to the time of occurrence, 55 species belong to archaeophytes, and 197 to coenophytes.

N.V. Plikina, A.N. Efremov, B.F. Sviridenko