An annotated list of 53 species of megachilid bees of the forest-steppe and steppe zones of the West Siberian Plain to the eastwards of Irtysh River is given. All previous data on distribution of Megachilidae in this region are summarized and critically discussed. Coelioxys echinatus Förster, 1853, Megachile pilidens Alfken, 1924 and Pseudoanthidium tenellum (Mocsáry, 1881) are recorded from the Asian part of Russia for the first time. Megachile melanopyga Costa, 1863 is new to the fauna of Kazakhstan. New data on distribution of megachilid bees in the different administrative regions of the West Siberian Plain are given also. Eoanthidium clypeare (Morawitz, 1874) and Lithurgus chrysurus Fonscolombe, 1834 are excluded from the fauna of West Siberia.