93 cryptorchid boys aged 1 to 6 years were treated with nasal spray of LHRH according with two different protocols: 0.4 mg thrice daily during 28 consecutive days in 39 (32 uni and 7 bilaterally cryptorchid) and 0.4 mg twice daily on alternate days three days per week for 1 month in 32 and 3 months in 22 (34 uni and 20 bilaterally cryptorchid). The results did not vary according to age or to the protocol and duration of treatment. Complete testicular descent was obtained for only 10% of unilaterally undescended testes, and reached 29% in bilaterally undescended testes. These results do not relate to the more or less high position of the testis nor to hypothetical changes in plasma gonadotropins or testosterone. The treatment had very minor side-effects. For this reason, in spite of its very limited results, it may be used either as an attempt before surgery at 4-6 years or as a means to distinguish retractile from undescended testes.