The aim of the present experiment was to qualify the relationships between microstructure of the muscle tissue and fattening, slaughter and meat quality traits of pigs. The experimental material consisted of 190 animals, representing Polish Landrace, Pietrain, Złotniki Spotted pigs and Pietrain × (Polish Large White × Polish Landrace) crosses. Samples of longissimus lumborum muscle were taken for histological tests and frozen in liquid nitrogen. After microscopic preparations were made, they were subjected to histochemical reactions to identify muscle fibre types differing in metabolism, and to determine the percentage of intramuscular fat and glycogen in the analysed muscle. The relationships between microstructure of the muscle tissue and fattening, slaughter and meat quality traits of pigs were expressed in figure enumerated corelation coefficients.On the ground of performed investigations the greatest rate of growth in pigs was connected with structure of muscle on thicker muscle fibres, possessing greater diameters. Differentiation of meatness in pigs was caused by occurrence of muscle fibres hipertrophy. Influence of histological structure of muscle on the some meat quality traits were observed, but the corelation coefficients between them proved low.

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