['To determine the optimal timing for orchiopexy, we evaluated the histological parameters of the cryptorchid testis.', 'We prospectively performed testicular biopsy in a total of 65 consecutive children with palpable unilateral inguinal cryptorchid testes. For controls, we used testicular histological slides from 15 age-matched children with testicular tumor. To investigate the fertility potential, we analyzed the parameters including mean tubular diameter (MTD), mean tubular fertility index (MTFI), germ cell count/tubule (GCC), Sertoli cell index (SCI) and interstitial fibrosis index (IFI).', 'The MTFI and GCC in children < or =1 years of age were significantly higher than those of other older age groups. The MTFI, GCC and IFI were significantly better in patients < or =2 years of age when compared to those of > 2 years. Compared to the controls, the MTFI and GCC in the patients were significantly worse in those aged > 2 years at surgical repair. In the < or =2-year age group, the MTFI and GCC of the cryptorchid testis showed a decreasing tendency with age, which were contrasting with the ascending curves in the control and the curves crossed at 1-2 years of age in each parameter.'] Do histological evidences suggest recommending orchiopexy within the first year of life for children with unilateral inguinal cryptorchid testis?