Morphologcal and Physiological Characteristics of Reproduction of the Stone Marten, Martes foina (Mammalia, Carnivora), in the Steppe Zone of the South of Ukraine. Steklenev, E. P. - Th e basic processes of the physiology of reproduction of the stone marten (Martes foina Erxleben, 1777) in the steppe zone of south Ukraine were investigated. They were found to occur mainly within the biological cycle of reproduction of this species, distributed in different geographical latitudes. It is characterized by a long period of gestation length (243-263 day) with a long latent period (June-July - end of February) and relatively short (15-16 months) period of actual pregnancy (late February-April). Termination of embryonic development is mainly on the stage of blastula. Implantation of embryos begins in late February, accompanied by processes of gastrulation and the formation of the amniotic membranes. Activation of spermatogenesis in adult males begins in late February and March, the formation of fullmature spermatozoa - in April. Males and females reach reproductive maturity mainly in the age of two years. A slight shift of individual processes of reproduction of the stone marten in the steppe zone of Southern Ukraine to earlier periods, compared with such of the northern latitudes, are due to more favorable climatic conditions of residence.