DIAGNOSIS of dissecting aneurysm of the aorta remains a difficult problem despite recent reports citing an increase in the number of correct antemortem diagnoses. The difficulty was summed up by Peacock1 in 1843: "Nor are the symptoms which attend its formation and progress such as can be regarded as characteristic of the affection," and reiterated 101 years later by White2: "There are no pathognomonic signs of dissecting aneurysms." Shennan's3 collection in 1933 of 300 cases of dissecting aneurysm included only 7 which had been correctly diagnosed. In 1944 Leitch4 collected 279 additional cases, 20% of which had been correctly diagnosed. Since that time, the number of reported cases has risen to well over 600, and correct diagnoses have been made in 15 to 83% of cases in recent series.5 The fact that a correct antemortem diagnosis was not made for any of the nine patients