*hCG stimulates Leydig cells leading to the increase in both intratesticular and circulating testosterone levels. The treatment with hCG alone is able to induce virilization, improve hypogonadism-related symptoms and, in some patients, to stimulate spermatogenesis. Co-administration of FSH is required to induce spermatogenesis in patients who are not responding to hCG alone. hCG is purified from the urine of pregnant women and administered intramuscularly at doses ranging from 1,000 to 2,000 IU 2–3 times a week. FSH is available as urine-derived human menopausal gonadotropin (hMG), highly purified FSH, and, more recently, as recombinant human FSH (rhFSH). Whereas hMG is a preparation containing FSH with variable traces of hCG, rhFSH and highly purified FSH have been introduced for providing preparations with pure FSH-like action. The dose usually employed ranges between 75 and 150 IU s.c. 2–3 times a week.