The effect of virus infection on the organism of pregnant mice and their posterity was studied in experiment. The animals were infected with the prototype strain A13 (Flores) of Coxsackie virus which was administered on days 4, 7, 11, 15 and 19 of pregnancy. It has been demonstrated that pregnant mice are much more sensitive to the virus than non-pregnant females and that the placenta, along with the striped muscles, is the main reservoir of the virus. The obtained results also suggest that the virus penetrates into the tissues of the embryo most intensively in the second half of pregnancy and that the duration of manifestation of the virus in the tissues of the embryo depends on the period of intrauterine development. The study of the model system (long-term organ culture of the tissues of the organism) enabled us to establish a new fact of the cytoproliferative activity of A13 Coxsackie virus in the organ culture and in the placenta of mice infected in vivo, and also in the organ culture of the liver of their newborn, which is important for the confirmation of clinical observations presuming a high probability of intrauterine infection by the mentioned virus with its subsequent protracted persistence in the organism of the newborn.