Several studies showed how serum levels of lactate dehydrogenase (LDH) are related with a worse prognosis and response to therapy. Its role in colorectal cancer is not still assessed. The aim of this study was to assess the prognostic role of serum level of LDH in non-metastatic, previously untreated, T2-T3-T4 colorectal tumours undergoing surgery. Data regarding preoperative serum levels of LDH have been retrospectively collected. A group with normal levels of serum LDH (group A) and a group with high levels of serum LDH (group B) have been identified and compared in relation with disease staging and outcome. A series of 96 cases have been analysed. Only age was significantly associated with increased LDH serum level (p 0.001). No significant differences between serum LDH levels, staging pT (p 0.721), pN (p 0.080) and grading (0.849) have been found. Test's sensitivity and specificity were 76 and 46.5%, respectively. Preoperative serum levels of LDH alone failed to demonstrate a prognostic role in a selected series of colorectal cancer patients. Low rates of sensitivity and specificity have been found.