Sialyl Lewis A (SLA) and sialyl Lewis X (SLX) have been shown to be specific ligands for endothelial leukocyte adhesion molecule-1 (ELAM-1), and may be involved in the process of adhesion between cancer cells and endothelium. We used immunohistochemical methods to study the expression of SLA, SLX and CEA in both primary tumors and matched metastatic liver lesions of colorectal carcinomas. Specimens from primary tumors and matched liver metastases from 24 patients with colorectal carcinomas were studied immunohistochemically. The degree of expression of CEA in liver metastases was similar to that in primary tumors, but SLA and SLX were expressed on a larger proportion of tumor cells in liver metastases than in primary tumors. Our findings suggest that colorectal carcinoma cells expressing SLA and/or SLX form metastatic liver tumors. They also suggest that expression of SLA and SLX in primary of colorectal carcinoma can be used as a prognostic indicator of metastasis.