The literature was reviewed for information on the long-term effects of cryptorchidism on fertility and cancer incidence. In unilateral cryptorchidism, treatment policies of orchidopexy alone, or of human chorionic gonadotrophin (hCG) therapy followed, if necessary, by orchidopexy, have resulted in similar levels of reduced fertility (15% azoospermia, and an additional 30% oligospermia, ie, sperm count less than 20 X 10(6)/mL). Very similar results were observed in unilateral cryptorchid men who had had no treatment (and were still cryptorchid at semen examination). In contrast, no untreated bilaterally cryptorchid men have normal fertility (sperm count greater than 20 X 10(6)/mL), whereas of those treated, a quarter have normal fertility. In some series, as many as half of the bilateral cryptorchid testes descended following hormonal treatment; a finding that could be attributed, at least in part, to the frequent difficulty in deciding on clinical examination, whether these testes are truly cryptorchid. There is little evidence that operation early rather than late within the age range of 4 to 14 years has any effect on subsequent fertility. Histologic studies suggest that orchidopexy should be carried out before age 2, but there are almost no follow-up data with which to evaluate the results of early operation. Since there is evidence that orchidopexy may result in testicular atrophy in a small proportion of cases, a trial of luteinizing hormone-releasing hormone (LHRH) may be advisable. There is little information available concerning the effect of age at orchidopexy on the subsequent risk of testicular cancer. Testes that cannot be brought into the scrotum should be excised.