Infections caused by bacteria of the genus Bacteroides, judged by our experience and by reports in the literature, are extremely rare, and, judged by the same criteria, cases of Bacteroides septicemia are still less frequently encountered. In a review by E. C. Rosenow Jr. and one of us1of 144 cases of septicemia with positive blood culture, exclusive of cases of subacute bacterial endocarditis associated with Streptococcus viridans, seen at the Mayo Clinic in the years 1934 to 1936 inclusive, Bacteroides was found to have been cultured from the blood stream in only 6 instances. In a later similar review by two of us2of 174 cases of septicemia with positive blood culture encountered in the three year period from 1937 to 1939 inclusive, Bacteroides was found as the causative organism in only 8 cases. In all of the foregoing instances as well as in 2 cases of