A normal functioning hypothalamic-pituitary-testicular axis is required for normal testicular descent. The percentage of cases that result from a disturbance in this axis remains controversial. Much has yet to be learnt about cryptorchidism, but is seems that the existence of A dark spermatogonia (Ad spermatogonia) is essential for later fertility. Bilateral cryptorchid patients have a high risk of later infertility, even though they undergo early surgery for cryptorchidism. It is possible today to distinguish—to a certain extent—between three different groups of cryptorchid patients based on testicular histology, gonadotropins, and inhibin B at the time of early surgery: Group 1, patients suspected of prepubertal transient hypothalamic-pituitary-testicular hypofunction and a high risk of later infertility; Group 2, patients with hypergonadotropic hypogonadism and a primary testicular dysfunction; and Group 3, patients with normal histology and normal serum levels of inhibin B and gonadotropins at the time of early surgery and a low risk of later infertility. Given the potential adverse effects of hormonal treatment, attention should be directed toward small doses of adjuvant gonadotropin-releasing hormone (GnRH) treatment for those who might benefit the most, that is, bilateral cryptorchid boys at early surgery without evidence of normal maturation of gonocytes into Ad spermatogonia. Optimally, gonadotropin levels in such patients should be measured to ensure that levels are not compensatory elevated, thereby supporting the suspicion of hypothalamic-pituitary-testicular hypofunction. Studies of GnRH-supplementary treatment should include testicular biopsy at surgery and at follow-up in childhood as well as examinations of fertility potential in adulthood.