The study guide presents modern concepts of blood as a tissue, the morphology and function of the formed elements of blood and lymph, features of the stages of embryonic and postembryonic hematopoiesis, and factors involved in the regulation of blood cell proliferation, growth, and differentiation. The modern theory of hematopoiesis is presented. The manual contains control questions and examples of situational tasks. The textbook is intended for students of medical universities in the specialties «General Medicine».