To evaluate the significance and the relationship between serum IAP level and the posto- perative pragression of the cancer, we measured IAP level in 42 stomach cancer patients, 11 colorectal cancer patients, and 12 breast cancer patients 2 years after curative surgery was performed as well as the preoperative IAP level of 54 stomach cancer patients, 28 colorectal cancer patients, and 24 breast cancer patients. 1) IAP level in preaperative stomach cancer patients was 596. 2+210. 5 g/ml, 51.8%. positive rate, and in postoperative patients, 352.8+67. 3 g/ml, 0 positive rate. 2) In preoperative colorectal cancer patients, IAP level was 519.8 +- 195.2 g/ml, 50.0% positive rate, and in postoperative patients 401.2+-140.3 g/ml, 9.1% positive rate. 3) In preoperative breast cancer patients, IAP level was 499. 6+ 170. 3 g/ml, 45. SM positive rate and in postoperative patients, 365.0+- 20.6 g/ml, 0% positive rate. 4) The change of IAP level as well as DNCB and T-cell count showed positive correlation with progression and surgical treatment in stomach cancer. We concluded that the measurement of serum IAP level in cancer patients is an useful tool as an immune parameter study for the postoperative progression of the cancer.