The paper presents the results of our long-term (August 2014–October 2016) observations of changes in some properties of the poisonous secretion of eastern steppe vipers of the nominative subspecies Vipera renardi renardi (Christoph, 1861) during their postembryonic ontogenesis. The poisonous secretion of newborn vipers differed from the venom of adult snakes by an increased protease activity and the absence of any L-amino acid oxidase activity; all newborns had colorless venom.