The most general usage of oat is for livestock feed. <...> However, oat consumption as human food has recently increased, perhaps due to its reported health benefits. <...> The abundance and species composition of the microbiota are the important factors in determining the quality of the grain. contamination of food commodities can affect both human and animal health. <...> The aim of this study was to evaluate the natural infestation by fungi of oat grain harvested in 2014 in the northwestern Russia. <...> Asymptomatic seeds of 56 oat samples harvested in five provinces of the northwestern Russia (7 samples from Arkhangelsk and Pskov provinces, 20 samples from Vologda Province, 12 samples from Leningrad province and 10 samples from Novgorod Province) were assayed for the presence of filamentous fungi. <...> Grain samples (except for a few unnamed) belonged to 14 varieties (Adamo, Argamak, Borets, Borrus, Krechet, Lev, LOS 3, Skakun, Scorpion, Teremok, Fukhs, Chernigovskiy, Chernigovskiy 83 and Yakov). <...> Seeds were surface sterilized and placed on Petri dishes with Potato-dextrose agar (PDA). <...> The resulting fungal colonies from each kernel were isolated and identified based on cultural and morphological features. <...> Fungal contamination and the percentage of species belong to or , , , , , , and others. <...> The main representatives of mycobiota were fection of and different regions ranged from 6.1 to 18.7 %, the maximum value was 64.0 %). fungi the , and , , , , were low-frequent For the first time fungi (%) were calculated in each sample. <...> Mycological analysis revealed presence of different species of fungi belonging to the genera , fungi. <...> Infungi was detected in 88.9 % analyzed oat samples (average grain infestation in fungi were found in 91.0 % grain samples (average infestation ranged 1.5 to 48.0 %, the maximum value was 85.0 %). <...> A number of species, such as , and , was found on the territory of Arkhangelsk Province which is the most northern border of this fungus areal in Russia. <...> The high positive correlation between portion of grains damaged by found. <...> Fungi of and genus were mainly presented by toxin-producing species (66-86 % of the total number of kov, Krechet were the most infected by The significantly higher grain infection by and accumulation of T-2/HT-2 toxins was isolates). <...> Cultivars Lev, Adamo, Ya(an average infestation rate was more than 20 %). fungi was detected <...>