A study was made of lutropin, follitropin excretion and the effect of testosterone on these parameters in men with hypogonadism. Apart from elevation (primary hypogonadism) and reduction (secondary hypogonadism) of the gonadotropin hormones production, of importance in the mechanism of sexual insufficiency is a change in correlation between luteinizing and follicles-stimulating hormones effects caused by lutropin deficiency or prevalence. Testosterone administered in the given pathology produced a different action on gonadotropin production (an inhibitory, stimulating, or none) depending on the level and intensity of the hypophysis-gonads system affection.