Of 1,125 patients catheterized over a period of 8 years, 68 (6%) had coronary ectasia. Twenty-five of them were catheterized at least twice and constituted the study group. The time between the first and last catheterization ranged from 2 to 8 years (mean ± SD = 4.2 ± 1.6). Coronary ectasia was more frequent in males (88%). The frequency of involvement was: the right coronary (47%), the left circumflex (30%), the left anterior descending (21%) and the left main arteries (2%). Proximal segments were most frequently involved (48%). Diffuse involvement was found in 29%. Severity of ectasia progressed in 6 segments (14%) and 2 new ectatic segments appeared over the follow-up period. During that period, 2 patients had myocardial infarction, 1 of them due to a total occlusion of an ectatic segment. There were no deaths. In conclusion, coronary ectasia has a relatively benign course.