This textbook was prepared by the staff of the Department of Biology and General Genetics of the I.M. Sechenov First Moscow State Medical University (Sechenov University) in accordance with the biology curriculum for students studying in the fields of healthcare and medical sciences. This edition has been revised and supplemented to reflect modern advances in biological and medical sciences, as well as the authors’ teaching experience. The textbook consists of two volumes. The first volume covers such areas of biology as cell biology, genetics, ontogeny, and phylogeny. It forms a foundational understanding of the organization and development of living systems and serves as a basis for further study of clinical disciplines. The second volume is devoted to medical parasitology and provides information on the most significant human parasites, including their morphology, life cycles, epidemiology, routes of infection, and methods of prevention. The material is presented in a systematic manner and is supplemented with tables, diagrams, and illustrations, which facilitate the comprehension of complex biological processes. The textbook is intended for students and may also be useful for instructors and specialists interested in the fundamental aspects of biology and medical parasitology.