Leucocyte migration inhibition test (LMIT) is a useful method to detect tumor associated antigens (TAA) in cancer patients. Carcinoembryonic antigen (CEA) is one of the best tumor markers for gastrointestinal cancer, and especially for colorectal cancer patients, who show high plasma CEA level frequently. In this study, we performed LMIT in 71 colorectal cancer patients with 3 M KCl extracts of cancer tissues and measured concentration of CEA in the plasma and the extracts of cancer tissue simultaneously. Although CEA in colorectal cancer extracts was individually varied from low to high in concentration, the levels of CEA had no relation to LMI reactivity. In addition, the LMI reactivity of colorectal cancer patients did not relate to the plasma CEA level of the corresponding patient. The results suggest that some antigens which induce leucocyte migration inhibition factor (LMIF) to lymphocytes from colorectal cancer patients might be different substances from CEA.