The book in a popular form tells about the biological role of vitamins in the vital activity of the body, the problem of vitamin deficiency in humans and farm animals. The following issues are covered in the relevant sections of the book: metabolism and circulation of substances in nature, methods of nutrition and nutrients, enzymes, functions of vitamins in the body, coenzyme functions of vitamins, vitamins and biological membranes, vitamins and health, water and fat soluble vitamins, antivitamins. Designed for a wide range of readers interested in this problem, students of medical universities and biological faculties of universities.