In order to study the effect on urinary hypophyseal gonadotrophins as measured by specific bioassays, 19 infertile men aged 26 to 47 years, average 30.8, were treated with clomiphene citrate (Clomivid®) 50 mg daily for 30 days. During the last 8 days of treatment 24 hour urine samples were collected daily for the determination of total hypophyseal gonadotrophins (HG), follicle stimulating hormone (FSH) and luteinizing hormone (LH). HG, FSH and LH rose equally to an average of 3 times the control values, the increase being highly significant statistically (P < 0.001). The most pronounced increase was observed in the cases with the lowest control values. Only one patient failed to respond. No side effects due to the drug were observed.