The aim of this study was to determine the antioxidant status and blood lipid profile of pigs fed diets enriched with α-linolenic acid (ALA) and containing two sets of antioxidants: phenolic compounds of diet components (barley, triticale, naked oat and buckwheat by-products) only, or phenolic compounds and vitamin E supplementation. A three-factorial experiment was performed on growing-finishing barrows (6-7 pigs per group) fed individually diets supplemented with 3% linseed oil, formulated as isoenergetic, isofibre and isofat. The influence of the type of diet (barley-triticale-based control diets vs 40%-oat-based diets), the share of buckwheat by-products (0 vs 10/12% of grower/finisher diets), and vitamin E supplementation (0 vs 100 IU⋅kg^-1) was evaluated. The analysed feed materials could be classified according to their total phenolic compound (TPC) content and in vitro antioxidant capacity (TAC) in the following decreasing order: buckwheat hulls and bran >> barley >> naked oat ≈ triticale. Diets with higher levels of TPC and TAC, i.e. barley-triticale-based control diets and diets containing buckwheat by-products, increased erythrocyte superoxide dismutase and glutathione peroxidase activity, similarly as 100 IU⋅kg^-1 vitamin E supplementation, thus suggesting an improvement in the antioxidant status of pigs. Only vitamin E supplementation significantly (over four-fold) increased vitamin E concentrations in the blood serum and M. longissimus dorsi (LD) of pigs, and decreased the rate of lipid oxidation in LD. The obtained results suggest that the phenolics present in cereal grains and in buckwheat, occurring as natural antioxidants in ALA-rich and vitamin E-deficient diets, are not sufficient to maintain the oxidative stability of pork. Diets containing 40% oat significantly improved the HDL/TCH and HDL/LDL ratios in serum.