Abstract
The antispermatogenic effect of niridazole was studied in 20 bilharzial male patients. Niridazole was found to induce defective spermatogenesis in the form of focal spermatocyte arrest and or germinal cell hypoplasia. The effect was transient, with active recovery occurring 3 months after therapy. Niridazole therapy must be postponed or changed for those subjects whose semen parameters prove to be subfertile.