Ascorbic acid (AsA) biosynthesis in the kidney of normal or hypophysectomized-castrated toads that received gonadotropins were studied. Hypophysectomy and castration or injections of LH decreased AsA biosynthesis. Administration of FSH in the hypophysectomized-castrated or normal toads increased biosynthesis of this vitamin. It is concluded that the AsA biosynthesis in the kidney of toads is regulated by pituitary gonadotropic hormones. © 1969.