The two serious complications of patent ductus arteriosus that occur most commonly are (1) cardiac failure due to the alteration of circulatory dynamics and (2) subacute bacterial endarteritis resulting from implantation of organisms at the site of the congenital abnormality. Gross,1in an attempt to correct circulatory abnormality and in the hope of preventing the future development of subacute bacterial endarteritis, was the first successfully to ligate a patent ductus. Since the report of this case in February 1939, Gross and Hubbard2have recorded eight additional operative cases and Bullock, Jones and Dolley3a series of eleven. The results in these twenty cases have demonstrated conclusively that ligation of the patent ductus is effective in correcting circulatory abnormality. Up to the present, subacute bacterial endarteritis complicating patent ductus has been treated by medical methods identical with those employed in cases of subacute bacterial endocarditis. It may be