Epithelial cells in the bone marrow of 42 patients with pancreatic carcinoma were identified immunocytochemically with monoclonal antibodies directed to epithelial cytokeratins. The occurrence of tumor relapse in patients who underwent complete surgical resection was significantly associated with cytokeratin-positivity in bone marrow. The presence of these cells in indicative of an increased disseminative capability of the primary tumor and defines a new category of patients for neoadjuvant therapy.