The textbook is written in accordance with the program for training students in the specialties: "General Medicine," "Pharmacy" and "Dentistry" - and on the basis of a course of lectures given at the medical faculty of RUDN University. Includes modern information on the biology of microorganisms, their pathogenicity factors, the structure and functioning of the immune system. Consists of 4 sections: general microbiology, infection, fundamentals of the doctrine of immunity, general virology.