CONGENITAL coronary arteriovenous fistula is relatively uncommon, but it must be considered in the differential diagnosis of patients manifesting continuous or to-and-fro cardiac murmurs. Only approximately 100 cases of this anomaly have been reported, and of these just over 50 have been treated surgically. Many of the cases treated surgically have not been recognized before surgery, but if arteriovenous fistula is suspected, the diagnosis can be confirmed readily by cardiac catheterization and coronary arteriography. Surgical treatment is very satisfactory, with a low operative mortality and apparent good long-term results.1-3 We present another case of congenital coronary arteriovenous fistula in which the diagnosis was made correctly prior to surgery and the patient was operated upon with successful closure of the fistula. The clinical features, method of diagnosis, hemodynamics and results of surgical repair are reviewed. The hemodynamics, as measured directly before and after closure of the fistula, seem particularly important