Barley yellow dwarf (BYD) is a worldwide disease of cereal crops caused by positive sense single-stranded RNA viruses of the genus Luteovirus (family Tombusviridae), and of the genus Polerovirus or unassigned species in the family Solemoviridae. Although BYD has been previously identified in Ukraine, the associated virus species infecting cereals are still unidentified. During the 2019/2020 growing season surveys for BYD were carried out in 24 fields in the cereal-growing regions of Ukraine (Vinnytsia [3 fields], Zaporizhia [2], Kyiv [11], Poltava [4] and Kharkiv [4]). From each field of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), rye (Secale cereale L.), oats (Avena sativa L.), or triticale (×Triticosecale Wittm. ex A. Camus) a composite sample of plants expressing symptoms of dwarfing, yellowing and redness was collected. The samples were tested for the presence of barley yellow dwarf virus (BYDV)-PAV, BYDV-MAV and cereal yellow dwarf virus-RPV by TAS-ELISA (Agdia, USA). BYDV-PAV was detected in wheat in Kyiv (2 of 6 fields), Poltava (1 of 3) and Kharkiv (1 of 4) regions whereas BYDV-MAV was detected in one of two surveyed oat fields in the Kyiv region. Serological detection of BYDV-MAV in a mixed oat sample was confirmed by RT-PCR using BYcpF/BYcpR primers (Kundu 2008). The 641 bp RT-PCR amplicon was Sanger sequenced (GenBank accessio No. MZ773946) and a 483 bp segment of the coat protein gene was analyzed showing that the BYDV-MAV isolate from oats named as BYDV-Ukr, has the highest homology of 99% to Polish BYDV-MAV and Estonian BYDV-GAV isolates (KU893149 and MK012663, respectively). The sequence data obtained in the study and results of ELISA tests clearly confirmed that isolate BYDV-Ukr belongs to the species BYDV-MAV, which was previously identified in wheat in Ukraine (Snihur et al. 2018). This is the first report of BYDV-MAV infecting Avena sativa in Ukraine.