Medical ozone is the universal stimulator which participates in intracellular biochemical processes. Treatment with intravenous ozone was studied in 35 women, 20 of them with gestosis Rhesus sensibility, 3--with anti-HLA antibodies, 5--pregnant with ABO sensibility, 3--with anti-sperm antibodies, and 7- with antivirus antibodies (Herpes 1,2 and CMV). As a result, ozone treatment is effective for decrease anti-erythrocyte and anti-leukocyte antibodies and other antibody levels in blood. Medical ozone has direct antiviral activity which induces long term remission and in some cases total elimination of virus from blood. Generally, ozone is a modulator of the immune system, stimulating links of humoral and cell immunity. It appeared that index of immune regulation (T-helper/T suppressor) in pregnant women was increased and level of immunoglobulins (Ig G, M, A) was within normal ranges. This work shows the results of chemical influence of ozone on the antibodies which subsequently the decreases the level of modifying immunoglobulins.