It has been explored the possibility of correction of prooxidant-antioxidant parameters at rats with experimental liver fibrosis and immunological status of these animals using xenogeneic embryonic stem cells. It is shown that the threefold sequential administration of copper sulfate in dose 1 mg / 100 g of body weight, which amounted to 30% of the lethal dose in 48 hour intervals between administrations induced liver fibrosis in 24 hours after the last administration to 3 month animals. It was found that the development of fibrosis, was accompanied 50 per cent increase in TBA-active products in the mitochondria and 25% of the increase in the microsomes of liver cells. Content of Ig A, IgM, circulating immune complexes (CIC) and the average molecular weight peptides was increased to 2-3 times in the same time. Introduction of xenogenic embryonic stem cells in animals with experimental fibrosis accompanied by decrease in the amount of TBA-active products to almost intact control. It coincided with the 60% increase in the activity of glutathione peroxidase in the mitochondria. Introduction of stem cells to experimental animals provide a normalization of the content of Ig A, Ig M, the CiC and the average molecular weight of the peptides.