The results of a microscopic examination of the internal organs of virally aborted fetuses are presented in order to determine the causes of reproductive losses in conditions of subclinical circovirus infection in sows. The material of the study was the tissues of the liver, placenta, umbilical cord, spleen and brain of abortion fetuses of sows whose pregnancy was interrupted in the last trimester of pregnancy. They had clinical signs of diseases associated with PCV-2 infection. It has been established that the PCV-2 virus has the ability to penetrate the feto-placental barrier from the mother's body; due to infection of the umbilical cord and placenta, it enters the fetus, in which it exhibits tropism in relation to the cells of the liver, spleen and brain. The development of the virus in the cells of these organs is the cause of the development of inflammatory, dystrophic and necrotic processes in them, affecting the processes of their intrauterine development, therefore in the last trimester of pregnancy, the cells of the liver, spleen and brain do not have functional properties corresponding to the duration of pregnancy, which affects their viability. The study demonstrates the role of circovirus infection in the formation of reproductive losses in sows in industrial conditions.