In this study, we attempted to detect K-raspoint mutations by means of two-stage polymerase chain reaction/ restriction fragment length polymorphism (PCR/RFLP) to diagnose micrometastases in paraaortic lymph nodes of patients with pancreatic adenocarcinoma. Main carcinoma tissues and corresponding lymph nodes in the paraaortic region were obtained from 15 patients who underwent extended radical surgery including the wide dissection of lymph nodes and who were diagnosed as lymph node negative by routine histological examination. DNA was extracted from the tissue specimens, and PCR/RFLP analysis was used to detect K-rasoncogene mutations at codon 12. Thirteen of the primary tumors were found to have K-rasmutations. In eight of the 13 cases, 42 of the 101 lymph nodes showed K-raspoint mutations in the paraaortic lymph nodes. These results suggested that PCR/ RFLP analysis is potentially highly sensitive for the detection of micrometastases in lymph nodes and that it may be useful in reaching an accurate assessment of the lymphatic dissemination of pancreatic adenocarcinoma at the molecular level.