The objective of the research study was to determine the effect of conformation and fatness classes of beef carcasses, assessed using a EUROP system, on meat quality. 216 carcasses from cows of the Black and White breed were studied in order to determine the relation between the m. longissimus thoracis quality and the EUROP classes. The carcasses analysed represented 3 conformation and 4 fatness classes. Under the quality assessment of m. longissimus thoracis (m. LT), a pH24 value was measured as were the colour parameters in the CIE L*a*b* system with the use of a Minolta CR-400 spectrophotometer. Also, the quality assessment performed included a marbling analysis. Based on the research results obtained, it was found that both the conformation and fatness classes were not related with the meat quality in the R and O conformation classes or with the fatness classes 2, 3, and 4. However, it was proved that the carcass meat of P conformation class and of the fatness class 1 was characterized by a higher pH24 value (p ≤ 0.01) and a higher incidence of discrepancies of DFD (Dark Firm Dry) type in the quality. Moreover, the carcass meat in the 1st fatness class was characterised by the lowest values of a* and b* colour parameters (p ≤ 0.01) and a lower marbling (p ≤ 0.01) in comparison to that of the classes 3 and 4. It The conformation and fatness classes of the cow meat were related to hot cow carcass weight that increased along with the higher degree of conformation (p ≤ 0.01) and the higher degree of fatness (p ≤ 0.01). The size of the surface area of the longissimus thoracis muscle did not depend on the fatness class (p ≤ 0.88) but it differed depending on the conformation class; it also showed a significant difference between the P class and the O and R classes (p ≤ 0.05).