The prognostic value of microinvasion of lymph vessels and lymph nodes has become increasingly important; there is a wide range in prognosis of patients with nodal-negative tumor stages after curative resection for colorectal cancer.Detection of the prognostic importance of isolated lymph-vessel invasion as a possible precursor of lymph-node metastasis in patients with nodal-negative tumor stages.Retrospective analysis of 894 patients with R0-resected colorectal cancer, uni- and multivariate analysis of tumorbiologic prognostic factors, immunohistochemical proof of tumor cells in negative lymph nodes (pN0) using the epithelial marker HEA-125 (human epithelial antigen).The incidence of lymph-vessel invasion (L) was 37.7% in total. A pN0,L1 status was found in 144 patients (16.1% of all analyzed patients). Comparing patients with pN0,L1 status to those with pN+,L0 status showed that both groups have similar rates of overall survival and tumor relapse. Lymph-node status, lymph-vessel invasion, depth of tumor infiltration (pT) stage, and age were detected as independent prognostic factors by multivariate analysis. After reanalysis of 54 cases primarily classified as 18.5% pN0,L1, microinvasion in lymph nodes was detected by immunohistochemistry. We found a higher rate of tumor relapse (approximately 20%) for those patients. In regard to the overall survival rate, however, there was no difference when compared to patients without immunohistochemical proof of microinvasion.Isolated lymph-vessel invasion in nodal-negative tumor stages and a lymph-node-positive tumor status have equivalent prognostic importance in colorectal cancer.