The article deals with the experimental data on the effect of the antihomotoxic preparation «Traumeel S» on the structure and function of the placenta in physiological conditions and in case of chronic hypoxia. The experiments were performed on 60 laboratory non-stock female rats, divided into four groups. The first group (n = 10) served as a control one. Animals in group 2 (n = 20) were subjected to hypoxia from the 10th to the 22nd day of gestation, at the same time receiving «Traumeel S» of 0.2–0.3 ml intramuscular injection every other day. Animals of group 3 (n = 20) were subjected to hypoxia, but they did not receive the preparation. The 4th group of rats (n = 10) received the preparation but was not exposed to hypoxia. On the 22nd–23rd day of pregnancy there was undertaken euthanasia to the rats and then histological examination of placentas was performed. The use of «Traumeel S» during pregnancy on the phone of hypoxia has a positive effect on the formation of the placenta, it stimulates the development of compensatory-adaptive processes in it.