Spontaneous coronary artery dissection is a rarely identified entity whose exact incidence, etiology, pathogenesis, medium-term evolution, and optimal treatment have not yet been firmly established. This article describes five new cases with additional specific characteristics. Five of 2,241 coronary arteriograms taken between September 1989 and November 1992 showed angiographic signs of coronary dissection. Three of the patients were treated pharmacologically, and two were operated on. All were evaluated angiographically 10-18 months after diagnosis and followed up clinically for > or = 20 months. Three patients exhibited acute myocardial infarction, one showed effort angina and the fifth unstable angina. In four cases, coronary dissection was associated with coronary atherosclerosis, but in the fifth the coronary tree was apparently healthy except for the dissection. Dissection affected the right coronary artery in three cases and the left in two. Angiographic evolution varied among the five and was uncorrelated with treatment. Dissection disappeared in three; it persisted, with total obstruction of the artery in the middle of the dissected segment in one case; and advanced to affect the whole left coronary tree in the fifth. After an 18-month follow-up, none of the five patients experienced symptoms. These cases provide a good illustration of the variability of spontaneous coronary dissection as regards etiology, clinical presentation, treatment, and evolution. Coronary dissection is always caused by hemorrhage in the media of the arterial wall; its variability in evolution and in optimal treatment may be derived from the cause of the hemorrage, which possibly was not the same in all cases.