The relationship between blood lipid indicators, subcutaneous and intramuscular fat contents and with the concentration of omega-3 fatty acids in the musculus longissimus dorsi (MLD) was investigated to search for biomarkers specifically associated with one of these relationships. The study was carried out on 32 gilts growing from 60 to 105 kg body weight (BW). The pigs were fed control (C) or experimental diets (L, M and H) in which 10% of metabolizable energy of diet C was replaced by 3.5% of fat mixtures that introduced in the different ratios of omega-3 fatty acids into the diets. The pigs were slaughtered at 105 kg BW and the serum concentrations of total protein (TP), triglycerides (TRIG), total cholesterol (CHOL), and high-, low-, and very low-density lipoproteins (HDL, LDL, VLDL, respectively) were determined. Backfat thickness, meat content in the carcass, and the fatty acid composition of MLD were estimated. Increased omega-3 fatty acid contents in the diet resulted in decreased concentrations of blood lipid indicators. TRIG displayed a significant correlation with meat content and backfat thickness in the carcass (r = –0.54, P < 0.01 or r = 0.43, P < 0.05). Also, a significant correlation was found between TRIG in the blood and the concentration of eicosapentaenoic and docosapentaenoic acids in the MLD (average r = –0.56, P < 0.01) and between CHOL in the blood and the concentration of linolenic acid in the MLD (r = –0.61, P < 0.01). Although the presented relationships were shown to be statistically significant, these blood lipid indicators should be viewed with caution as biomarkers specifically associated with carcass fatness.