The purpose of the research is studying seasonal dynamics of gastrointestinal strongylatosis in bison in the Central Region of the Russian Federation.Materials and methods. The bison of different age and sex was studied in the Prioksko-Terrasny Nature Reserve, the Moscow Region. Fresh feces collected near feed troughs in enclosures in different seasons for three years were examined according to generally accepted methods. To analyze the infection rate of gastrointestinal strongylates in the European bison by months throughout the year, we took average monthly temperature and humidity values for 2018, 2019, and 2020 into account.Results and discussion. The maximum number of positive samples was diagnosed in the warm season of the year, namely, in summer and in the first months of autumn: August, September and October 2018 (79.3, 83.3 and 82.9%), August, October, November and December 2019 (73.7, 76.9, 77.1 and 77.8%), and June, July, August and October 2020 (85.6, 87.2, 88.0 and 86.3%). Ambient temperatures and precipitations affect significantly on the time of larvae development in the environment, which can be clearly seen in 2019.