Based on new material from the Omsk Oblast, southwestern Siberia, Russia, the distributions of two geophilomorph and four lithobiomorph centipedes have been refined. Both the genus Pachymerium C.L. Koch, 1847 and the species P . ferrugineum (C.L. Koch, 1835) are recorded from the Omsk Oblast for the first time. Two more lithobiid species, Lithobius vagabundus Stuxberg, 1876 and L. . ( Ezembius ) ostiacorum Stuxberg, 1876, are also new to the Omsk Oblast. The distributions of all species encountered are mapped within the study area.