This publication is devoted to animal biochemistry - the science of molecular processes occurring in the cells of living organisms. Knowledge of biochemistry is necessary to find out the causes of the pathology of various diseases and find ways to effectively treat them. The textbook meets the tasks facing the discipline "Biochemistry"; considers the structure and properties of the main biogenic molecules (nucleic acids, proteins, lipids, carbohydrates, vitamins, hormones, etc.), as well as metabolic processes occurring in cells of various organs and tissues.