There were 35 hypofertile men who underwent assay of serum follicle stimulating and luteinizing hormones, and testosterone, and were placed in a trial program using clomiphene citrate in a 25-day cycle, with 5-day rest periods. Therapy has been maintained for up to 9 months with a projected termination of 12 months. No relationship could be established between serum follicle stimulating hormone and spermatozoal number in this population. The spermatozoal count improved in 31 men while they were on therapy and 8 pregnancies have occurred. Clomiphene citrate seems to be effective in improving the quanttity of spermatozoa and the spermatozoal motility in these hypofertile men.