Objective of research: Determination of the efficiency of 5% concentration Diminazene aceturate at the dose of 0.25 mg/kg body in combination with polyethylene glycol solution applied against piroplasmidosis in cattle. Materials and methods: Trial of the new method of prolonged chemoprevention was carried out in one of the farms of Dagestan, which is unfavorable for piroplasmidosis. Aceturate contained in this drug rapidly inhibits DNA in cells of blood parasites, which leads to their death within several hours. Diminazene aceturate proved to be effective against piroplasmidosis, babesiosis, taleriosis, hemosporidosis of animals. The experiment was conducted on 30 head of cattle divided into 3 groups 10 head in each. Animals of two groups received the preparation and prolongator at the dose of 0,25 mg/kg in the 15% aqueous solutions of polyethylene glycols (PEG), and at the dose of 0,25 mg/kg in the 20% aqueous solutions; the third group served as a control (received the preparation without prolongator). Efficacy of the method was estimated by periodic examination of blood smears from experimental animals for plasmodia in erythrocytes and synchronous measurement of body temperature of animals. Results and discussion: It was found that the method of prolonged chemoprophylaxis applied against piroplasmidosis in animals (at the dose of 5 ml per 100 kg body weight, 6 times every 25 days) enables disease prevention during the whole disease season. Such method allows reducing the number of treatments from 24 to 12-13 times in a season. In addition, data on the distribution of hemosporidia infections among the cattle in the Republic of Dagestan were clarified.