The paper analyzes William’s Garvey’s many achievements. In particular, he rejected the hypothetical constructs created by his predecessors and discovered the basic laws of blood circulation. W. Harvey ascribed the closure of circulation to the direct connection of arteries and veins through tiny tubes; these tubes are the capillaries that were discovered by M. Malpighi only 4 years after the death of W. Harvey. He was the first to refer the liver to as a protective barrier organ. W. Harvey had ideas of the functions of the blood circulatory system by 1615, but his classic work “Exercitatio anatomica de motu cordis et sanguinis in animalibus” (“An Anatomical Study of the Motion of the Heart and Blood in Animals”) came out in 1628. W. Harvey is justly considered to be one of the founders and creators of modern embryology. His second book «Exercitationes de generatione animalium» («Studies on the Generation of Animals») was published in 1651. It summarized the results of long-term studies of the embryonic development of invertebrates and vertebrates (birds and mammals) and concluded that «an egg is the common origin of all animals» («Ex ovo omnia»). Both oviparous and vivíparous animals (mammals and man) originate from eggs. Until very recently, the most important actual discoveries and some ideas by W. Harvey have not, however, lost their relevance in this area. He disproved the judgment of spontaneous self-generation. W. Harvey opposed the theory of preformism, considering that beings develop from eggs, «by adding parts separating from one after another», and introduced the concept of epigenesis. His studies of mammalian embryology gave the largest incentive to the development of theoretical and practical obstetrics.