The objective of this study was to determine the chemical composition and fatty acid content in m. longissimus dorsi (MLD) of two indigenous pig breeds (ML -Swallow-belly Mangalitsa and M -Moravka) reared in free range farm conditions and fed complete mixtures used for commercial meat pig genotypes. The body mass of ML and M pigs at slaughter was,on average, 107.14 and 107.61 kg, respectively. In MLD of M pigs, more total fat was measured compared to ML breed (6.96 % compared to 5.10 %, P<0.05). Protein content in MLD of ML pigs was higher by +0.92 % (P<0.01) compared to M pigs. Male castrates of M pigs had more fat compared to gilts of the same breed (8.64 compared to 5.29 %), and the 3.35 % difference between mean values was statistically significant (P<0.05). The breed of pigs influenced the total saturated fatty acids (P=0.011) and mono-unsaturated fatty acid (P=0.003) contents, but not the content of polyunsaturated fatty acids (P=0.325). In the case of saturated fatty acids in the MLD of ML and M pigs, the most common were C16:0 (25.05 % and 25.53 %) and C18:0 (12.73 % and 14.40 %). The MLD of M pigs contained 1.67 % more stearic acid compared to ML pigs (P=0.004). Pigs of ML, compared to M pigs, had more C18:1cis-9 (+2.31 %), C16:1 (+0.49 %), C17:1 (+0.10 %) and less C20:1cis-11 (-0.25 %). The content of two essential fatty acids, C18:2n-6 and C18:3n-3, did not vary according to breed or sex of pigs (P>0.05). The n-6/n-3 ratio was higher than optimal (18.7 for breed ML and 13.7 for M).