The effects of AVT [arginine-vasotocin] on the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by rat anterior pituitary cells in monolayer culture were examined. Because AVT fails to modify the basal or the LR-RH [luteinizing hormone-releasing hormone] stimulated secretion of either FSH or LH by pituitary cells in culture, AVT probably does not inhibit synthesis or release of gonadotropins by the pituitary. If AVT is involved in the regulation of gonadotropin secretion, the site of action is probably the hypothalamus where it may modulate secretion of LH-RH.