28978 cases of young (after the 14th year of age) and adult patients autopsied during the period from 1.1 1951 until 31. 12. 1969 in our Institute were scored for coronary thrombosis and analysed concerning frequency and distribution of age and sex, resp. In this material the evidence of morphological changes was proved by longitudinal dissection of the coronary vessels. We analysed the age of thrombi, the localization and the grading of coronary vessels occlusions. Coronary thrombi were found in 2,31 per cent of all autopsies (2,81 per cent in males,1,31 per cent in females). Coronary thromboses showed an increase during the observation period. These thrombi were found more frequently in younger patients. Most of the thrombi (62,20 per cent) were localized in the Arteria coronaria sinistra, 37,80 per cent we found in the Arteria coronaria dextra. Fresh thrombi (57,51 per cent) and those being in organization (42,49 per cent) were not significantly different. Obturating thromboses showed an increase. The numbers of non-obturating thromboses decreased during the observation period. Our findings correspond to similar results published in literature.