In the last few years, the poultry industry has been affected by abnormalities in chicken breasts, which are described as modern myopathies. These are white striping, wooden breast and spaghetti meat defects. A common feature of modern myopathies is their occurrence especially in fast-growing genotypes of chickens fattened to a higher live weight. Although these myopathies have many common histopathological manifestations, they are easily macroscopically distinguishable. In many cases, the mechanisms of individual defects are not known. Modern myopathies affect poultry meat production in many countries, thus negatively and fundamentally affecting the economy of production. An important impact of the occurrence of individual defects is the reduced consumer acceptance.