Background: The present work was based on the evaluation of histological, histochemical, and quantitative study on the adrenal medulla of the white albino rat in the different post natal age period. Material and methods:Sixty male albino rats were used in this study. The rats were classified to 4 main groups as follows:             - Group one : One week old albino rats. - Group two:  One monthold albino rats. - Group three: Three months old albino rats.        - Group four: Senilerats. Three main parameters were performed in this study, the first was the study of the morphological changes in the adrenal medulla in the different postnatal age groups. The second was concerned with the histochemical studies while the last parameter was the quantitative studies on the gland volume as well as its cellular count. These three parameters were performed by using different staining techniques.      Results: The results showed that medullary cells in the early age groups were arranged in non-differentiated groups and become more differentiated in the older age groups. Both reticular and elastic fibers in the older age groups showed a definite increase especially at the region of corticomedullary zone. The different types of chromaffin cells were more observed at the old age groups.  The concentration of ascorbic acid granules was more marked in the senile group. The quantitative changes were in the form of increased medullary volume especially in the old age. The number of chromaffin cells as well as the concentration of ascorbic acid contents was more noticed in the old age group. Conclusions: The differentiation of both divisions of the adrenal gland was not noticed in the early age groups. Cellular and fibrous differentiations were more seen in older age groups which may reflects an idea about the degree of gland maturation.