Eighty of Sarcoma 180 bearing mice, averaging 30 gm of body weight, were divided into eight groups of animals receiving Saline as the control, Corynebacterium parvum, Tubercin-3 and Cyclophosphamide alone and Cyclophosphamide combined with C. parvum, with Tubercin-3 and with both C. parvum and Tubercin-3 and Tubercin-3 combined with C. parvum respectively. Treatment was initiated 4.8 hours after tumor implantation and repeated three times once a day. Doses were suspended or dissolved in 0.2 ml of Saline: 1.4 mg of C. parvum: 0.5 micrograms of Tubercin-3; and 2.7 mg of Cyclophosphamide either in alone or in combination. All the agents given were administered subcutaneously but Cyclophosphamide was given intraperitoneally. The observation on the general conditions of animal took place twice a day following the treatment until the time of death after tumor implantation was determined. Average survival days in each group were as follows: In Control, Saline (11.2 days), C. parvum (14.8 days), Tubercin-3 (16.7 days), Cyclophosphamide(18.7 days). In combination therapy, Cyclophosphamide with C. parvum(22.8 days) with Tubercin-3 (26.9 days). Cyclophosphamide with both C. parvum an Tubercin-3, however, was somewhat longer than in Cyclophosphamide alone but shorter than in combined with either one of C. parvum or Tubercin-3. Finally, in combination with immunotherapeutic agents, Tubercin-3 and C. parvum each other it (8.2 days) was shorter even than Control. Life span of host is, in generally, inversely related to the number of malignant cells and conclusively, the therapeutic potentiation was reflected to be extended survival in combined treatment of a chemotherapeutic Cyclophosphamide with either one of immunotherapeutics, Tubercin-3 or C. parvum. Tubercin-3 and C. parvum in combination, however, appeared to be antagonistic each other.