A doctor's thesis was discussed at the College of Agriculture at University of  Basrah (extraction of hyaluronic acid from Streptococcus thermophilus and studying its antioxidant activity for sunflower oil and its effect on some physiological parameters) The thesis of the researcher (Amir Abbas Muhammad), under the supervision of (Prof. Dr. Alaa Karim Naimah), included the extraction of hyaluronic acid from a local bacterial isolate from different samples of local milk located in the local markets of Basra Governorate. The isolation was confirmed by biochemical, phytic and 16S tests rRNA, the optimal conditions for acid production were studied from the bacterial strain S. thermophilus (ABST) grown on alternate medium containing whey at 450 ml/l and yeast extract at 7.5 g/l at temperature at 40°C for 18 hours, 3% inoculum volume and pH 6.8 Using the incubator at a speed of 150 revolutions/min, the acid production was 0.598 g/l and the biomass amount was 6.08 g/l. Then the hyaluronic acid produced from the bacterial strain ABST grown on the standard and alternative medium was identified using three techniques HPLC, FTIR and NMR for the nucleus of hydrogen atom (proton) 1H And carbon 13C atoms in the presence of standard hyaluronic acid as a comparison sample, and the results showed the similarity of peaks and bundles of the produced acid with the standard acid, and its physical properties of viscosity, molecular weight and For thermogravimetric analysis and differential scanning calorimetry. The antioxidant activity of hyaluronic acid was also estimated by testing its ability to capture free radicals (DPPH), reducing power, hydrogen peroxide (H2O2) capture and ferrous ion binding using different percentages of acid ranging between 50-1300 µg/ml and the concentration 1300 µg/ml gave the highest antioxidant activity. The produced acid was applied as a natural antioxidant to hinder the oxidation in crude sunflower oil at different storage periods 0, 30, 60, 90 days, and using different concentrations of acid ranging between 100-600 mg/kg oil, and the concentration of 600 mg/kg oil gave the best effectiveness. Inhibitory to inhibit oxidation in oil packed in dark containers and during all storage periods. The effect of feeding experimental animals with ration containing sunflower oil added to hyaluronic acid as a natural antioxidant for 42 days did not affect the physiological parameters of experimental animals and increased their weights. The study concluded that hyaluronic acid can be used as a natural antioxidant that replaces industrial antioxidants in prolonging the storage life of vegetable oils. The study recommended the use of modern techniques such as genetic engineering and the transfer of genes responsible for acid production to the bacterial strain to increase its production and include it in other food products such as yoghurt, meat products or pastries in order to improve the functional properties of these products.