The relationship between Dexamethasone proliferative activity and the presence of glucocorticoid receptors was studied on a human glioblastoma cell line (HU 197). For this purpose, the 17 beta-Carboxamide steroid DXB, a glucocorticoid antagonist that competes with Dexamethasone for binding to the intracellular glucocorticoid receptor but does not trigger the glucocorticoid effect, was used. Concurrent treatments with Dexamethasone and DXB caused an inhibition of the proliferative effect obtained by Dexamethasone. The results obtained demonstrated that the Dexamethasone activity on cell proliferation is a specific receptor-mediated effect.