THE ENTITY of ruptured sinus of Valsalva has been known to pathologists for many years, the first report having been published in 1840 by Thurnam.1 Since then the condition has been described on many occasions, but it was not until 1956 that this defect was successfully repaired by operation.2-4 The increasingly widespread use of extracorporeal circulation and a growing awareness of the clinical manifestations and operability of this syndrome have resulted in a moderate number of cases being operated on. Because the mortality rate of operation using extracorporeal circulation is remarkably low, it seems worthwhile to report three additional cases as a means of reemphasizing the pitfalls in diagnosis and treatment, and at the same time to encourage operation as a safe and satisfactory means of treating this condition. Report of Cases Case 1. —A 40-year-old man had been symtomatically well most of his life. However, early in