The doctoral thesis in the Department of Food Sciences, Faculty of Agriculture, University of Basrah discussed (extraction and characterization of biologically active peptides from locally manufactured dairy products). Dairy products The study included the manufacture of (yoghurt and cheddar cheese) from cow and buffalo milk for the purpose of obtaining peptides and using them as natural antioxidants. A week and during these periods, the peptides were extracted using the gel filtration technique weekly, and their antioxidant activity was studied and the best period for decomposition and formation of biologically active or active peptides was selected. Cheddar cheese was also made from cow and buffalo milk that was preserved after maturation in refrigeration at a temperature of 7 ° C and stored for periods of time. The peptides were extracted using gel filtration technique using ÄKTA Pure 25 device (the latest chromatographic technology in Iraq) during different periods (12, 8, 4, 2, 0) weeks. On four peaks, two of cow's milk yoghurt, the peptides of the first and second peaks showed high antioxidant activity compared to the rest of the peaks at a concentration of 10 mg/ml, which amounted to 69.96% and 89.88%, respectively. Two peptides were obtained from buffalo milk yoghurt, with their antioxidant effectiveness for the first and second peaks reaching 68.76% and 87.76 percent, respectively. Two peptides were also obtained from cow and buffalo milk cheddar, with an antioxidant effectiveness of 82.4% and 85.4%, respectively, compared with other antioxidants. The natural alpha-tocopherol, ascorbic acid, and the synthetic antioxidant BHT, as well as the estimation of the amino acids in each peptide, were obtained, as 16 amino acids were obtained at different concentrations. Factors affecting the stability of peptides such as different salt concentrations, different temperatures, and pH were also tested. These peptides were also applied in ground beef discs and extended their storage life. The study aimed to identify the biologically active compounds that are formed during the manufacturing processes in the dairy industry and which have a role in the metabolic processes inside the living body, as well as extracting the biologically active peptides from milk products and using them as inhibitors or antioxidants for free radicals. The thesis recommended the use of biologically active peptides as natural antioxidants in prolonging the storage life of food products instead of industrial antioxidants, as well as increasing the consumption of fermented dairy products produced from natural milk to increase the production of antioxidants in vivo.