The investigations included meat and fat samples taken from carcasses of 10 mass-reared fatteners in the central- eastern part of Poland. As for 24 samples of acids taken, the highest values of saturated acids were stated in the lard. The highest per cent fraction of monounsaturated acids was determined in the longissimus lumborum and semimembranosus muscles: 57.92% and 56.74%, respectively; a much lower values were found in the stock fat: backfat: 49.79% and lard 42.97%. The highest level of polyunsaturated fatty acids was stated in the stock fat (lard: 12.74%, backfat: 12.74%). If comparing the content of fatty acids in the two analyzed muscles, a higher proportion of saturated acids was stated in the longissimus lumborum muscle (36.98%). As for mono- and polyunsaturated acids, the situation was just contrary to this one: both acids showed higher values in the semimembranosus: 57.92% and 7.64%, respectively. As for the longissimus lumborum muscle, the NNKT/NKT ratio amounted to 1.7, and in the semimembranosus to 1.9. Similar tendencies were stated with regard to the stock fat: higher values of saturated acids were found in the lard: 44.27% and the level of monounsaturated acids was higher in the backfat: 49.79%. No significant differences were found between the lard and the backfat with regard to the overall content of polyunsaturated acids. The unsaturated/saturated acids ratio in the stock fat was 1.69 as for the back fat, and 1.26 as for the lard, respectively.