The c-erbB-2 and cyclooxygenase (COX) pathways are involved in the pathogenesis of colorectal carcinoma, but the relationship is not fully understood. This study evaluated the significance of c-erbB-2, COX-2, and Ki-67 protein expression in 185 patients with colorectal carcinoma using tissue microarrays. Only one case expressed cerbB-2 protein. COX-2 expression was noted in 166 of 176 cases (94.3%), and the Ki-67 expression rate averaged 5.9%. There was no relationship among c-erbB-2, COX-2, and Ki-67 protein expression, and COX-2 protein expression was not related to tumor stage, differentiation, size, depth of invasion, lymphatic or vascular invasion, or patient survival. While the contribution of c-erbB-2 to colorectal carcinogenesis may be of little quantity, COX-2 may be deeply involved in colorectal carcinogenesis.