The article shows the life and scientific career of the famous physiologist, scientist, doctor of veterinary sciences, professor, corresponding member of the National Academy of Sciences Rostyslav Fedoruk. It describes the scientific, pedagogical, organizational and public activities of the professor. The results of fundamental research and applied developments obtained by R. Fedoruk during the performance of tasks that were part of the scientific programs of the NAAS and the Scientific and Methodological Center “Animal Physiology” are presented. The main results of the theoretical and applied research conducted under the leadership of R. Fedoruk regarding the influence of new effective feed additives and biologically active substances tested and implemented in production, in particular in cattle breeding, sheep breeding, rabbit breeding, poultry farming and beekeeping, and proposals and methods about their use are substantiated. Rostyslav Fedoruk is the author of more than 500 scientific works, including monographs, textbooks, reference books, etc. For a long time he was the deputy editor-in-chief and a member of the editorial boards of numerous scientific publications, a member of the Ukrainian Biochemical and Physiological Societies, the T. Shevchenko Scientific Society. Since 2015, he has been elected vice-president of the Ukrainian Physiological Society named after P. Kostyuk. The scientific activity of R. Fedoruk and his students is devoted to studying the processes of adaptation in animals to agroecological conditions of keeping, elucidating the physiological and biochemical mechanisms of the influence of biologically active additives on the main and intermediate exchanges, the reproductive function and productivity of farm animals, and the assessment of the biological value of animal husbandry products. During the period of persistent creative and scientific-pedagogical activity, R. Fedoruk gained a strong authority as a scientist and enjoyed deep respect among his colleagues, influenced the formation of Ukrainian agricultural science and formed his scientific school of researchers.