The investigation was carried out on 62 fatteners divided into groups according to their origin (big farms vs. family farms) with the aim of investigating differences in their carcass composition. At the slaughter line, carcass weight, muscle (M) and fat (S) thickness were determined and leanness was calculated according to “Two points” and EU reference method. Carcasses of the pigs originating from modern farms were lighter compared to carcasses originating from family farms; however, two groups did not significantly differ from each other in the cold carcass weights. Animals originating from family farms had higher back-fat thickness and lower leanness determined by “two points” and EU reference methods. Despite similar ham weight, pigs originating from family farms had lower share of the fat in the carcass with higher share of fat the tissue (subcutaneous and intermuscular) with lower weight and share of the muscle tissue compared to animals raised on modern farms. Animals originating from family farms had higher loin weight, with higher weight and share of fat tissue and bones comparing to animals originating from modern farms. Pigs raised on modern farms had higher loin weight and share of the muscle tissue, as well as higher weight and share of the muscle tissue of loin in the carcasses. The investigated groups did not differ in weight and share of shoulder in the carcass, however, pigs originating from family farms had higher weight and share of subcutaneous fat tissue compared to pigs originating from modern farms. Share of the muscle tissue in shoulder, as well as the share of shoulder muscle tissue in the carcass was higher in pigs originating from modern farms. Pigs raised on family farms had significantly higher weights and shares of belly-rib part, as well as it’s intermuscular and subcutaneous and bone tissue compared to pigs raised on modern farms, while pigs from modern farms had significantly higher share of belly-rib muscle tissue, as well as muscle tissue of the belly-rib part in the carcass. The investigated pig groups did not differ in weight and share of tenderloin in the carcass. The classification of the carcasses into commercial classes revealed that 21.88% of the carcasses originating from modern farms were classified into S class, 46.88% into class E, 18.75% into class U and 12.50% into class R, while 3% of the carcasses originating from family farms were classified into S class, 30% into E class, 43.33% into U class, 16.67% into R class and 7% into class O.