The human immunoglobulin (SM-4300), which was developed by Travenol Laboratories, Inc. U.S.A., was used with antibiotics on 12 cases of severe surgical infectious disease. The method of administration and the evaluation of clinical effect of gammaglobulin (SM-4300) were made based upon the criteria of the SM-4300 study group. The clinical evaluation of the effect was classified in 5 grades; excellent, good, fair, poor and unknown. Three types of administration dose schedules were employed. Severe surgical infections were 3 cases of postoperative pneumonia, 3 cases of sepsis with pneumonia, 3 cases of peritonitis, 1 case of cholangitis, 1 case of sepsis with perinephritis and 1 case of subphrenic abscess. Bacterial and immunological examination were also performed before and after the administration of SM-4300. Evaluable cases were 10 cases out of 12 cases. Clinical effects of the administration of SM-4300 were evaluated as excellent in 1 case, good in 3, fair in 2 and poor in 4.