An intermediate in testosterone biosynthesis, found in the testis or the adrenal glands. Androstenediol, derived from dehydroepiandrosterone by the reduction of the 17-keto group (17-hydroxysteroid dehydrogenases), is converted to testosterone by the oxidation of the 3-beta hydroxyl group to a 3-keto group (3-hydroxysteroid dehydrogenases).