The objective of this study was to determine the effect of the concentration of C18:3 n-3 and the total concentration of polyunsaturated fatty acids (PUFA) and n-3 PUFA in the diet on the performance of pigs, carcass characteristics, and fatty acid profile of intramuscular fat of Musculus longissimus dorsi (MLD) and subcutaneous tissue (ST) fat. Twenty-four crossbred pigs ♂Duroc x ♀(Polish Large White x Danish Landrace) were divided into 3 groups (A, B, and C) and from 60 to 105 kg body weight (BW) were fed isoenergetic (average 13.5 ME MJ·kg^-1) and isolysinic (average 7.4 g·kg^-1 standardized ileal digestible lysine) diets in which 10% of the metabolizable energy had been replaced by fat mixtures totaling 3.5% per kg diet. Diet A contained 1% rapeseed oil, 2% fish oil, and 0.5% lard; diet B contained 2.5% rapeseed oil and 1% linseed oil; and diet C contained 2.5% linseed oil and 1% fish oil. The diets had similar amounts of C18:2 n-6, but differed in the amounts of C18:3 n-3 (ALA), 20:5 n-3 (EPA), and 22:6 n-3 (DHA). Fat mixtures in the diet did not influence growth, carcass performance, lipid or fatty acid concentrations in the tissues of the pigs, but changed their PUFA concentration. ST fat compared with MLD fat had a higher (P<0.01) ratio of both PUFA/SFA (0.61 and 0.38 vs 0.74 and 0.32 vs 0.77 and 0.41, respectively, in groups A, B, and C) and PUFA n-6/n-3 PUFA (9.0 and 4.45 vs 6.18 and 3.82 vs 3.99 and 3.51, respectively, in groups A, B and C). Meat and fat from pigs of group C had PUFA/SFA and PUFA n-6/n-3 PUFA values consistent with WHO recommendations. Thus, it can be concluded that supplementation of the diet for pigs with a mixture of linseed oil and fish oil makes it possible to obtain good quality pork with health-promoting properties.