Using a standard heterologous assay in which lymphokines alter guinea pig peritoneal macrophage migration, it was found that regional lymph node cells (RLNCs) from patients with primary breast cancer elaborate soluble factors which variably affect such migration. Variation of migration resulted when soluble factors employed were obtained from different nodes in the same patient as well as from nodes from different patients. Some nodes from a patient elaborated migration inhibition factors (MIF) and other migration enhancing factors (MEF). The findings are in keeping with others obtained by us relative to the variation in lymphocyte transformation and thymidine uptake by RLNCs and further emphasize that all RLNs in patients with breast cancer are not biologically similar. They lend support to our previous hypothesis that the reason why some RLNs contain metastases and others do not is more likely due to biological differences than because of anatomical happenstance, i.e., transport of tumor cells to some nodes and not to others.