The role of tissue CEA determination as a complementary test in the staging of colorectal cancer and monitoring of the marker in the follow-up of patients, is stressed. In a group of 44 colorectal cancer patients, tissue CEA was determined by the immunoperoxidase assay in the apical and cytoplasmic portion of tumor cells, stroma, glandular lumen, and cytoplasm of superficial and deep cells. A correlation has been observed between spread and stage of tumor and CEA localization at the level of the stroma and cytoplasm of deep cells. It has been also evidenced that in all cases where CEA was present in the stroma and cytoplasm of deep cells, high serum levels of the marker were detected.