Determining the degree of safety of new antiparasitic drugs for veterinary use is based on the results of a whole complex of preclinical study. The quality and effectiveness of preclinical studies are guaranteed by compliance with the rules provided for in normative documents, which are harmonized with international standards. However, due to the exploratory nature of such studies and the variety of methodological approaches used, there are no strict criteria for planning experiments. The choice of methods and tools when planning work on the preclinical evaluation of safety and efficacy of antiparasitic agents should be based on the specifics of their chemical structure and application to the target animals. The paper considers approaches to the regulation of preclinical toxicology studies of antiparasitic agents for veterinary use, taking into account their usually high or medium toxicity, the ability to cause death or impaired functions in living things (both the parasite and the host) and short-term use of the target to animals. The use of such approaches will make it possible to unify the methodology of experiments, to ensure the reliability and reproducibility of the results of preclinical pharmacology studies, and to increase their scientific and practical significance.