Histomorphological changes in testicular parameters and seminiferous epithelium of different age groups male donkeys; pre-pubertal-pubertal and post-pubertal periods were observed. The present study was performed on Testes of 14 donkeys obtained from local markets from Menoufia governorate. Animals divided into four age groups (pre-pubertal-pubertal - post-pubertal and senile after the collection, gross anatomical features of the testes were examined and recorded. The present anatomical result showed that the testis of the donkey was not completely descended into the scrotum around birth. The mean weight, length and width of both left and right testicles in groups differed significantly (p≤0.05) from each other. The both testicles were appeared not symmetrical, the left testes were larger than right one. All morphmetrical parameters were significantly increased when age advanced. The beginning of seminiferous epithelial cycle at 1.5 years old. Marked morphmetrical changes in donkey testes occurred from period of puberty until middle of sexual maturity at 6- 7-year-old after that a serious of regressive changes occurred. A marked increase in the weight and diameter of the testes was recorded at 2-6-year-old; The parenchyma of testis was dark reddish in color; it was covered by a thick tunica albuginea consisting of outer and inner fibrous layers in addition to middle vascular one. The diameter of the seminiferous tubules was greatly increased than those recorded at the early stage of the postnatal development. The present histological results emphasized an irregular arrangement of the testicular lobules of the donkey during various stages of the postnatal life. Such arrangement does not allow some lobules to have direct contact with the mediastinum testis. Numerous seminiferous tubules with different shapes and size were highly active.