The complete genome of Uzun-Agach virus (UZAV), isolated from the liver of Myotis blythii oxygnathus (Monticelli, 1885 (Chiroptera; Vespertilionidae)) bats in Alma-Ata district (Kazakhstan) in 1977 have been sequenced. Based on full-length genome comparison it is shown that UZAV is a new member of the Nairovirus genus (family Bunyaviridae). L-segment and M-segments of UZAV have 69,3% and 64,1% identity with Issyk-Kul virus (ISKV) that also was isolated from bats. S-segment of UZAV have 99,6% identity with the same of ISKV. This allow us to claim that UZAV is a reassortant virus that have S-segment derived from ISKV, and L- and M-segments from another virus that is phylogenetically related to ISKV, but divergent from it. The obtained data that the reassortment between ISKV and UZAV exists in nature suggest that they cocirculated in one ecological niche (bats of the Vespertilionidae family) and the areal of UZAV may coincide with the areal of ISKV.