The experiment material comprised 124 hybrids derived from crosses of black-and-white cows, their Holstein Friesian breed genes content not exceeding 25 %, with black-and-white bulls (25 animals) and meat bulls (99 animals). The objective of the research was to compare the histological traits and physicochemical characteristics of beef meat depending on the incidence rate of giant fibres in skeletal muscles of black-and-white bulls and commercial crossbreeds. It was shown that the giant fibres were more frequently present in the muscles of animals crossbred with meat breeds. As for the commercial cross-breeds, they were evidenced in 42 % of the animal population, and as for the group of black-and-white bull population: in 20%. The presence of giant fibres was associated with a higher myofibrillar ATPase activity, whereas the transformation of FTO fibres in the relevant muscles produced higher percentage rates of FTG fibres (54.4 – 58.5 %), as well as an increase in the relative cross-section area of anaerobic fibres and anaerobic index (AnF%) (4.18 – 5.47). The muscles containing giant fibres were found to be more frequently quality deficient: a pH48 value exceeded 5.8, their colour was darker, their water retention capacity was higher.