The monograph is devoted to the fauna, peculiarities of ecology and distribution of ixodoid ticks in biogeocenoses of Uzbekistan. Physiological and biochemical mechanisms of tick-host interrelations are analyzed. Toxic characteristics of bioactive substances of salivary glands of dominant ixodes and argas ticks are presented. The publication is intended for zoologists, parasitologists, entomologists, veterinarians, workers of sanitary and epidemiological services, students of biological, veterinary and medical profiles.