Male contraception is still an unresolved problem because scientists do not yet clearly understand spermatogenesis, particularly hormonal regulation and identification of growth factors responsible for spermatozoa development. Suppression of luteinizing hormone and of follicle stimulating hormone is a possible approach. Yet, it takes 60 days to achieve azoospermia and it is necessary to substitute an androgen. Despite the fact that many trials using steroids (androgens, progestins and androgens) or a gonadotropin releasing hormone (GnRH) agonist with androgens have been conducted, not every subject achieves azoospermia. Initial trials of GnRH antagonists in association with testosterone enanthate show that this combination achieved azoospermia in almost all subjects. This approach must be improved by developing long acting antagonists and a more physiological testosterone substitution. Another approach, which inhibits reversible secretion of gonadotropins, leans toward the production of an anti-GnRH vaccine. So far, studies have not produced acceptable results, despite a reduction in the production of spermatids. No animal achieves azoospermia. Isolation and cloning of human sperm surface glycoproteins would lead to another type of contraceptive vaccine. This antigen would prevent sperm from joining with the egg.