The paper presents macroscopically analyzed 2600 segments 0.5 cm of length of all three main coronary arteries in 50 consecutive autopsy cases suffering from ischemic (coronary) heart disease. A quarter of segments had had a "critical" lumen narrowness (75% of more). The greatest concentration of "critical" lumen narrowness is within the first 6 cm of length. Similar distribution of "critical" lumen narrownesses was found in the first 4 cm of length of circumflex branch of left coronary artery with a remark that concentration of examined segments was higher between the second and fourth cm. The greatest concentration of "critical" lumen narrownesses was not established, because these segments are evenly arranged along the first 10 cm, when examined according to the assumed thirds. Single coronary disease was found in 10% of cases, double coronary disease in 44%, triple coronary in 44% and stenosis of the left coronary arteries in 2%. On the average 2.3 coronary arteries with "critical" lumen narrownesses were found in each case.