Phytohemagglutinin (PHA), T-cell stimulator, concanavalin A (ConA), stimulator upon various T-cell subjects, Pokeweed mitogen (PWM), T-cell stimulator and partial B-cell stimulator, and lypopolysaccharide (LPS), B-cell stimulator in animals, were applied to patients with cancer of advanced stage. The changes in blastogenesis of peripheral blood lymphocytes before and after operation or administration of levamisole (immunostimulator) and effectiveness of levamisole were studied. The postoperative changes in relative values of PHA ConA/PHA, PWM/PHA, were also examined. The results were as follows: 1. Blastogenesis of peripheral lymphocytes against PHA, ConA and PWM decreased, paralleling progress of cancer. 2. LPS-blastogenesis was different from the above mentioned 3 kinds of mitogen but it also decreased with progress of cancer. 3. In curative resection, the order of the value in blastogenesis was PHA > ConA > PWM > LPS. In non-resected cases, it was ConA > PWM > PHA > LPS. When the value of ConA/PHA, or PWM/PHA was greater than 1, the prognosis were worse. 4. In cases who received levami sole, the decrease in blastogenesis of lymphocytes against each mitogen did not in blastogenesis of lymphocytes against each mitogen did not occur. 5. Each mitogen was thought to react upon various subjects of lymphocytes which did not overlap with each other.