We treated 78 boys with 103 undescended testicles with luteinizing-hormone-releasing hormone (LHRH) nasal spray, 400 micrograms 3 times daily for 4 weeks. After one (28 testicles) or two (5 testicles) courses of LHRH, 33 testicles in 25 boys were in the normal scrotal position. The success rate is 32%. In 41 testicles (40%) the result was a better mobility and/or a further descent, facilitating the proper diagnosis or the operation. 70 testicles were operated, and anatomic abnormalities were seen 37 times. In 6 boys minor side effects were noted. Reviewing the literature there is agreement that LHRH spray sometimes is necessary to confirm the presence of a retractile testicle, and so can be used in trying to avoid an operation.