The purpose of the research is studying the tolerability profile of drug» Gelmintal Mini Syrup» based on toltrazuril and moxidectin in therapeutic and increased doses administered once and repeatedly to target animal species. Materials and methods. The experiments were carried out on 45 cats and kittens, and 45 dogs and puppies. In each experiment, the animals were divided according to the principle of analogy into three groups of 5 animals each. In the first experiment, the drug was administered once in two- and 5-fold increased doses; and the animals were followed-up for 30 days. In the second experiment, the drug was used daily for 7 days in therapeutic and 3-fold increased therapeutic doses; and the animals were followed-up for 15 days. During the experiments, we recorded the animals’ general condition, behavior and appetite, monitored their body weight and temperature, and collected blood and urine to study a number of parameters that characterize the physiological state of experimental animals. Results and discussion. «Gelmintal Mini Syrup» in therapeutic and increased doses administered once and repeatedly does not adversely affect the general condition of cats and dogs. Hematological, biochemical and urological values were within the physiological range.