Histologic and electron-microscopic studies were carried out on pale-soft-exudative (PSE) and pale-soft (PS) swine meat taken from musculus longissimus thoracis et lumborum. PSE meat was shown to have more strongly manifested morphologic changes. Histologically, with some of the samples there were 'gigantic fibers', their dia exceeding several tens of times the dia of fibers taken from control animals. The electron microscopy with some of the samples revealed a strong deformation of the myofibrils (extensions alternating with narrowings), broader Z-bands, loss of striation in the anisotropic zones, confluence of myofibrils in individual portions, granular destruction or fragmentation of sarcoplasm with swollen or disrupted mitochondria in it, strongly disrupted or destructed Z-bands, lysed or hyperchromic nuclei of the fibers, etc. In PS meat the same ultrastructural changes were observed, although they were less strongly manifested. With such meat some of the samples showed total destruction of the Z-bands, which had led to the full separation of sarcomeres (a phenomenon observed for the first time). These results constitute a contribution to the knowledge of the mechanism through which the PSE meat phenomenon occurs and the evaluation of such meat for consumption.