In situ expression of intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), and vascular cell adhesion molecule-1 (VCAM-1) was investigated in 20 human colorectal cancers using immunohistochemical techniques. Tumor microvessels, detected with endothelial marker Ulex Europaeus Agglutinin-I (UEAI), were consistently present within both stromal and glandular areas. Vessels expressing cell adhesion molecules (CAMs) were less frequent but more common within the tumor stroma. Although ICAM-1 and ELAM-1 vessel staining was present in all tumors, ICAM-1 staining was the most consistent with primary localization to stroma while ELAM-1 was variable with localization to both stroma and glandular areas. VCAM-1 staining was inconsistent and was rare in glandular areas. A significant increase in the number of vessels expressing CAMs with a concomitant decrease in the total number of vessels was noted in bowel muscularis adjacent to tumor compared to remote bowel. No relationship between number of vessels or frequency of CAM positive vessels and tumor site, grade, or stage was noted. These studies demonstrate enhanced microvascular expression of CAMs in close proximity to colorectal tumors despite decreases in total number of vessels, suggesting that factors within the tumor microenvironment effect tumor microvascular development. Correlation between these studies and previous microscopic studies suggest that vessels expressing CAMs play a role in immune cell infiltration and may provide new targets for anti-tumor therapies.