A 47-year-old man with heterozygous familial hypercholesterolemia was followed up by coronary angiography for 9 years. During these 9 years, he experienced inferior myocardial infarction twice, at segment 1 of the right coronary artery. A coronary atherosclerotic lesion (50% stenosis) was also present at segment 6 of the left anterior descending coronary artery. This lesion remained unchanged for the first 7 years, but then rapidly progressed to 90% stenosis in the 8th year. While the rate of the progression of coronary atherosclerosis is generally unpredictable, it may progress rapidly in this case of heterozygous familial hypercholesterolemia.