Induction of angiogenesis is essential for the continued growth of solid tumors, and one critical component of tumor-induced angiogenesis involves the stimulation of microvascular cells to migrate into the growing mass. We have developed a convenient model system utilizing dual co-culture chambers to study cellular chemotaxis induced by glioma cellsin vitro. In this system, rat C6 glioma cells induced migration of fibroblasts and brain capillary endothelial cells. The migratory response was directly related to the number of C6 cells serving as stimulus in the lower chamber. Similar migratory responses were induced by C6 cell conditioned medium in a concentration dependent fashion. Medium conditioned by cultured human anaplastic astrocytoma cells was also found to contain potent chemotactic factor(s). This system may ultimately be employed in the identification of particular glioma cell population(s) and secreted factor(s) responsible for the chemoattraction of microvascular cells.