In order to correlate the date of balano-preputial separation (BPS) with the testicular development, twenty four rats were selected from an experimental design focused on the effects of pituitary grafts on puberty. Animals that presented BPS at an early age, showed a smaller volume of the seminiferous epithelium and a lower spermatogenic level than that presented BPS at a more advanced age. These data indicate that the advancement in BPS induced by pituitary grafts was not in keeping with an equivalent enhancement of testicular development.