Objective of research: to determine the toxicological properties of the preparation Cyflunit- Flock under acute experimental conditions at oral and subcutaneous administration routes to laboratory animals. Materials and methods: White outbred mice and white outbred rats of both genders were used for testing. Each dose of the preparation was tested on groups of males and females to identify the eventual sex differences in drug-responsiveness.In experiment on mice, animals were divided into 5 groups of 10 animals each.The medicine was given orally at the doses of 4350, 8700, 13050, 17400 and 21750 mg a.i./kg. In experiment on rats, 4 experimental male and 4 female groups were formed (6 animals in each). The drug was given orally at the doses of 17400 and 21750, 26100 and 30450 mg a.i./kg. While studying the acute cutaneous toxicity, Cyflunit- Flock was applied at the doses 870, 1740, 4350 and 8700 mg a.i./kgin 4 experimental groups of male and 4 groups of female rats of 6 animals each. Observations of general health status, behavior of animals, intoxication symptoms and eventual death of animals were conducted within 14 days. Results and discussion: LD50 of Cyflunit-Flockat oral administration to mice of both genders was 12180 mg/kg,at oral administration tomale rats - 22475 mg/kg, to female rats - 23925mg/kg. At cutaneous use of the preparation in rats, LD50 was more than 8700 mg/kg. Accordingtothestandardhygienicclassification, the preparation belongs to the 4thhazard class (low-hazard substances).