Eighty-nine oligozoospermic men, treated by clomiphene or tamoxifen or with no treatment at all, were evaluated during a 4-year follow-up period. Ejaculate volume, sperm concentration, and sperm motility were determined and concentrations of prolactin (PRL), estradiol, beta hCG, prostaglandin E2, zinc, and fructose were ascertained. Isoenzyme LDH-C4 activity and serum PRL and follicle stimulating hormone were also determined. During treatment there was only a minimum increase in sperm concentration. No improvement in sperm motility and no alteration in ejaculate volume were observed. The pregnancy rate was lower in the partners of patients receiving treatment (23.8%) than in the partners of those receiving none (29.6%). Statistically the difference is insignificant. After antiestrogen therapy, prolactin concentrations in serum decreased and zinc concentrations in seminal plasma increased. For the treatment of idiopathic oligozoospermia in infertile men, clomiphene and tamoxifen were ineffective medication.