Femoral artery perfusion for cardiopulmonary bypass is still employed for reoperation, procedures involving the thoracic aorta, and partial bypass in critical patients. Retrograde aortic dissection is the most significant complication of femoral perfusion. The reported incidence is from 0.6% to 14% with a mortality of 66%. Most of the deaths occurred in patients in whom the dissection was not recognized , or in whom the dissection was recognized but not treated appropriately. Our experience with retrograde dissection totals six patients of 640 (0.9%) in whom femoral inflow was used. Four of the six patients survived the dissection. Sudden increase in extracorporeal line pressure shortly after beginning cardiopulmonary bypass associated with decreased venous return, dampened radial arterial pressure, and the abrupt appearance of a bluish, bulging ascending aorta establishes the diagnosis. Survival is enhanced if cardiopulmonary bypass is promptly discontinued, aortic cannulation established, and bypass reinstituted with the induction of profound hypothermia. Circulatory arrest may then be employed to repair the false passage. In this series the proposed operation was completed in all six patients.