Abstract. This study examined the effect of different fat supplements on the antioxidants of cow’s milk. Thirty five Polish Holstein Friesian cows at 180±20 day of lactation and averaging 17.71±2.26 kg/d of milk were divided into five equal groups. There were five treatments groups: 300 g/d of fish oil, 500 g/d of Opal linseed, 500 g/d of Szafir linseed, 150 g/d of fish oil + 250 g/d of Opal linseed, 150 g/d of fish oil + 250 g/d Szafir linseed. Milk samples were collected five times during the 21 day of supplementation period: at the 1st, 14th and 21th day of the experimental period, and also at the 14th and 21st day after the supplement withdrawal. Diet supplementation with the Szafir linseed improved the chemical composition and milk yield at the 21st day of experiment. The highest level of malondialdehyde was recorded in fish oil, Opal linseed, fish oil + Opal linseed, and fish oil + Szafir linseed groups, and the lowest in the Szafir linseed group. After the 21st day of supplementation the concentration of α-retinol was significantly increased in all groups by 23 to 183 %. The highest level of α-tocopherol was found in fish oil + Opal linseed group at the 21st day of supplementation. Total antioxidative status increased in all experimental groups; however, the highest peak was recorded in fish oil + Szafir linseed and Szafir linseed group. The experiment confirmed that manipulation in cows’ diet may improve antioxidative capacity of milk.