It is a definite possibility that organs which are primarily elements of functional systems other than the reproductive system are involved in sexual maturation. The adrenal glands are attractive candidates for such a role in sexual maturation : they are capable of producing androgens, oestrogens and progesterone, not only in the adult, but also in the prepubertal animal. This points to the adrenal cortex as source of hormonal material that may be directly involved in sexual maturation. Studies in which adrenalectomy, followed by reimplantation of the adrenal glands, was performed, provide proof that medullary degeneration does not influence sexual maturation (Gorski & Lawton, 1972, 1973.We will review here the main lines of available evidence on involvement of the adrenal glands in sexual maturation. Emphasis will be on the female rat which has been studied most extensively. The following topics will be discussed. (1) Hormone production by the adrenal glands during sexual maturation. This background information seems important if a possible role of the adrenal glands in sexual maturation is considered. (2) Interactions that have been observed between adrenal gland function and the reproductive system in the prepubertal animal. Although existence of such inter¬ actions does not necessarily give (direct) proof of adrenal involvement in sexual maturation, it does perhaps indicate how the adrenal glands may contribute to sexual maturation. (3) Experimental alteration of adrenal function and sexual maturation : under this heading we will discuss the various parameters of sexual maturation that have been studied after experimental manipulation of adrenal function, in which the approach has been largely restricted to adrenalectomy. (4) Finally, we will discuss whether, when established, an influence of the adrenal glands on sexual maturation must be attributed to a specific interaction of the adrenal glands with the hypothalamo-pituitary-ovarian sys¬ tem or whether it is due to more general effects of adrenal function on bodily development. It is well-known that the stage of bodily development reached is a decisive factor in sexual maturation.