At autopsies between 1951 and 1969, 246 of 2393 cases with myocardial infarctions and heart muscle scars showed no thrombi and no artery sclerosis to be worth mentioning. The 7 comprehensive morphologically investigated observations of a second case group were discovered in a prospective study from 1970 to 1973. This study included 255 cases with myocardial infarctions or heart muscle scars. Comparatively to the investigations with sclerosis of the coronary arteries, myocardial infarctions without occlusive coronary disease were stated more frequent in woman than in men. Furthermore, more young people were affected from these infarctions. In 3 of 7 cases without sclerosis or thrombosis of the coronary arteries the infarctions were located more frequent subendocardial that in these cases with coronary sclerosis or thrombosis. Respectively to the size the 246 infarctions of the first group, they did not differ from those taken in a respecting group of 2147 cardiac infarctions with stenosing processes of the coronary arteries. Infarctions without sclerosis or thrombosis of the coronary arteries were located more frequently in the ventricular septum and in the wall of the right ventricle. For these infarctions a coincidenceof several, separate not relevant factors in supposed to be the cause. Theinfarctions without stenosing processes of the coronary arteries occupy insome respects an exceptional position, but on principle they do not differ in the morphological findings from the other myocardial infarctions.