B. M. Zavadovsky, prominent physiologist and endocrinologist, and director of the K. A. Timiriazev State Biological Museum, was born 110 years ago. He was a pupil of physiologist I. P. Pavlov, botanist K. A. Timiriazev, and geneticist N. K. Kol'tsov. Zavadovsky studied the role of hormones in humans and animals. In the 1930s he proposed a theory of synthesis and metabolism of hormones in the organism, which later led to the development of gonadostimulants. His methods for curing infertility, testing pregnancy at an early stage, and determining the embryo's sex found wide applications in medicine, and also in animal husbandry. Zavadovsky was also active in the popularization of science and in museum work, and he took part in philosophical discussions about genetics and evolution. After his principled opposition to Lysenko at the August 1948 session, Zavadovsky was fired from his official positions and consigned to oblivion.