Twenty-eight patients had infections due to Clostridium septicum ; 21 of them had documented septicemia. A malignancy was present in 23 of the 27 patients for whom hospital records were available. In three, an intestinal tumor was found one to two months after C septicum was cultured. In contrast with wartime reports, no wound infections due to this organism were observed in otherwise healthy individuals. Of the 27 patients, 13 of 15 treated with antibiotics survived, but 11 of 12 in the untreated group died. In each case the source of the organism was probably the patient's own intestinal tract.