A formulation for male contraception comprising a progestin possessing both estrogenic and androgenic properties is remarkably effective for spermatogenesis suppression in males. The progestin Norethisterone (NET), particularly its derivatives Norethisterone acetate and Norethisterone enanthate in sufficient doses induce oligozoospermia or azoospermia in males. Formulations further comprising an androgen, such as a testosterone derivative such as a testosterone ester, particularly testosterone undecanoate, are especially effective male contraceptive formulations.