The purpose of this study was to evaluate the pattern of the expression of orotate phosphoribosyltransferase (OPRT) in several components of colorectal carcinoma (CRC). Fifty-six surgically-resected samples of CRC were subjected to immunohistochemistry with a polyclonal anti-OPRT antibody. Grading was performed independently for several components of CRC, including mucosal carcinoma lesions (n=56), infiltrative lesions (n=53), lymphovascularly invasive lesions (n=34) and metastatic lymph nodes (n=17). The expression of OPRT in mucosal carcinoma and infiltrative lesions correlated significantly only with the presence of lymphovascular invasion (p=0.0007 and <0.0001, respectively). The frequency of OPRT expression in mucosal carcinoma, infiltrative and lymphovascularly invasive lesions as well as metastatic lymph nodes was 32.1, 69.8, 88.2 and 88.8%, respectively. In addition, nuclear staining of OPRT was observed in metastatic lymph nodes and lymphovascularly invasive lesions. Our results suggest that OPRT is involved in the invasion and metastasis of CRC.