Inhibin B immunocytochemistry of both the alpha- and beta-subunits was studied in testicular biopsies from 18 prepubertal and postpubertal patients, with unilateral or bilateral cryptorchism. The present investigation was carried out to seek any prognostic significance for the expected fertility of such subjects in adulthood. All samples were also evaluated by histological and morphometric assessments, according a 1-6 grading sy-stem. In this way, the individual testicular changes were scored by quantitating tubular and germ cell hypoplasia, Sertoli cell hyperplasia, and peritubular fibrosis, where present. The results showed that in bilateral maldescended testes an unexpected expression often occurred of inhibin B beta-subunit in Sertoli cells, while inhibin B alpha-subunit there did not, denoting an early developmental arrest of the testis. It co-related with the high grade testicular damages, as a poor predictor of spermatogenesis. Unlike, unilateral retained testes mainly expressed inhibin B alpha-subunit, irrespective of tubular changes. In the latter instance, different pathogenetic factors of imbalanced testicular regulation can be perspected, other than the Inhibin-Activin system.