Infertility has been considered a principal complication associated with cryptorchidism. A particularly high incidence of cryptorchid boys lack the priming effect during the first 3 months of life due to low concentrations of gonadotropins and testosterone (inadequate perinatal stimulation of the testes, which causes infertility). This condition causes impaired transformation of gonocytes into fetal spermatogonia. More pronounced hypogonadotropic hypogonadism results in fewer germ cells. Most importantly, cryptorchid boys with fewer than 0.2 cells per tubular cross section have a high probability of being infertile in adulthood, regardless of whether the condition is unilateral or bilateral and despite apparently successful orchiopexy. To counteract the paucity of priming hormones, cryptorchid patients with unilateral or bilateral cryptorchidism and a severe paucity of germ cells were treated with a low dose of the luteinizing hormone-releasing hormone analogue buserelin after successful orchiopexy. We analyzed the spermiograms of these patients, who are now young adults, and compared them to those of 23 other men who also had cryptorchidism with a comparable severe paucity of germ cells but who had not received hormonal treatment after successful orchiopexy. Patients who received hormonal therapy after orchiopexy had significantly improved spermiograms compared to those in the control group. Treatment with buserelin increased the number of spermatozoa, improved motility and increased the number of normal forms of spermatozoa. The luteinizing hormone-releasing hormone analogue buserelin, administered as a nasal spray every other day for 6 months following successful orchiopexy, appears to have a long lasting, positive effect on germ cells. Consequently, the prognosis of fertility has been greatly enhanced in patients treated with buserelin.