The investigations were conducted using 283 pig carcasses slaughtered in three meat plants: ‘Łmeat’ Łuków, ‘Morliny’ near Ostróda, and ‘Prime Food’ Przechlewo. The left half-carcasses were divided into main joints and, subsequently, four joints were dissected according to a method of Walstra and Merkus. The investigation showed that among the four dissected joints under analysis the highest percentage of meat was found in leg (67.67%) and shoulder (63.32%), whereas the lower percentage of meat was in loin (54.16%) and belly (49.86%). The highest percentage of subcutaneous fat with skin was found in loin (28.13%) and belly (24.99%), whereas the highest percentage of inter-muscular fat was found in belly (18.48%) and shoulder (9.11%). As for bones, the highest percentage of this component was detected in loin (10.82%) and shoulder (9.32%), and the lowest in leg (7.55%) and belly (6.01%). There were obtained very high correlation coefficients between the meat percentage levels in leg and loin, and the percentage level of this tissue component in the sum of four dissected joints (r = 0.974 and r = 0.976). It was stated that on the basis of the dissection of a single joint, it is possible to more precisely asses the percentage of subcutaneous fat with skin in carcass than the percentage of inter-muscular fat. The highest correlation coefficients between bones percentage of meat in the single joint and the percentage level of this tissue component in the sum of four dissected joints were achieved for the loin (r = 0.888) and leg (r = 0.842), whereas lower coefficients were determined for shoulder (r = 0.767) and belly (r = 0.592). Thus, it is suggested a dissection of leg in order to estimate the muscularity of pig carcass because its percentage in carcass is high and its muscles are easy to separate. It is accentuated the importance of correct splitting carcasses in half-carcasses for the purpose of assessing the percentage level of bones in carcass on the basis of the loin’s bones.