PURPOSE: This study aimed to provide immunohistochemical evidence of micrometastasis in patients with node-negative Dukes' B colorectal cancer and to evaluate the clinical implications, including prognostic significance, of lymphatic metastasis. METHODS: A retrospective study of 90 patients who underwent a curative operation due to colorectal neoplasms from 1996 to 2001 was performed. Two consecutive sections of lymph nodes were prepared: one for ordinary hematoxylin-eosin staining, and the other for immunohistochemistry with pancytokeratine antibody. All clinical factors, including survival rate, were compared between patients with and without lymph-node metastasis. The mean follow- up period was 36.1 months. RESULTS: Micrometastasis was confirmed in 115 nodes (7.9%) from 32 patients (35.6%). No correlations were observed between micrometastases and prognostic factors, including survival rate, except for lymphatic invasion and postoperative TNM staging. Twenty-six of the 32 (81.3%) patients with micrometastases belonged to stage T3N0M0 (P<0.003). CONCLUSIONS: The immunohistochemical assay may be a useful way to identify micrometastasis in patients with Dukes' B colorectal neoplasms, but we were not able to demonstrate the prognostic significance of micrometastasis.