This preliminary report describes a new method of treating bilateral cryptorchidism that may modify the need for surgical intervention. Four of five boys (3 1/2, 3 1/2, 7, 11 and 12 1/2 years of age) given hourly subcutaneous pulses of luteinizing hormone-releasing hormone (LH-RH, 10 to 100 micrograms/day, given in a 3-min pulse every hour) showed evidence of testicular descent after 3 to 19 weeks. The battery-operated, programmable syringe driver was well tolerated by the boys, and the daily insertion of the scalp-vein needles was managed at home by their parents.