The main infectious diseases of ungulates caused by helminths, ticks, insects, protozoa, bacteria and viruses are considered. The questions of etiology, biological features and resistance of pathogens, distribution and clinical manifestations of diseases are highlighted. Attention is paid to modern methods of diagnosis, treatment and prevention of infectious diseases of horses. Part 1 is written by Professor P. I. Khristianovsky, V. V. Belimenko, A. M. Gulyukin, A. I. Laishevtsev and E. V. Novosad; part 2 is written by Professor K. P. Yurov and S. V. Alekseenkova. It is intended for students studying in the specialty "veterinary medicine", practical veterinarians and a wide range of horse lovers.