To assess the effect of LH-releasing hormone (LHRH) and hCG in the treatment of cryptorchidism, 33 articles published in English between 1958-1990 were analyzed. Altogether, 3282 boys with 4524 undescended testes were included in the analysis; 872 boys with 1174 undescended testes were treated in randomized trials. The meta-analysis showed LHRH to be more effective than placebo; the risk ratio was 3.21 [95% confidence interval (CI) of 1.83-5.64] and 2.57 (95% CI, 1.39-4.74) in trials excluding retractile testes, respectively. In the combined randomized trials, the success rate with LHRH was 21% (95% CI, 18-24%), that with hCG was 19% (95% CI, 13-25%), and that with placebo was 4% (95% CI, 2-6%). The effect of the hormonal treatment was overestimated in nonrandomized trials. In conclusion, LHRH is effective in the treatment of cryptorchidism, and hCG is more effective than placebo, but data about the effect are scanty.