This study was done on 14 buffalo's adrenal glands. The adrenal gland of buffalo consisted of outer cortex and inner medulla. It was surrounded by thick CT capsule. The thickness of the capsule varied according to the age of the animals. It was thin (242.6 ± 12.1 μm) in young and thick (265.3 ± 13.2 μm) in adult animals. Thin septa extended into the parenchyma of the gland. The cortex consisted of three distinct zones, zona glomuralis (Arcuata) which was (385.5 ± 13.9 μm) in young animals while (415.7 ± 14.6 μm) in adult animals. The columnar cells of the arcuata contained numerous round mitochondria and smooth endoplasmic reticulum , while few rough endoplasmic reticulum. Zona fasiculata, which was the widest zone of the gland (865.6 ± 17.5 μm) in young animals while (912.8 ± 18.3 μm) in adult animals. The cuboidal cells of the zona fasiculata showed numerous round and oval mitochondria , small round electron-lucent lipid droplets , well developed Golgi complex and smooth endoplasmic reticulum. Zona reticularis which was (432.2 ± 14.3 μm) in young animals while (471.3 ± 15.8 μm) in adult animals. The cells contained round mitochondria, Golgi complex and less vacuole.The medulla was consisted of outer part that separated from the cortex by CT capsule. The thickness of the medulla was (457.8 ± 15.2 μm) in young animals while (482.5 ± 16.6 μm) in adult animals .It consisted of large columnar cells with dense eosinophilic cytoplasm and large oval basophilic nuclei. These cells showed small, round electron-dense oval granules with variable densities and size. Mitochondria are present but less numerous than that of the fasicuolata cells .It considered adrenaline secreting cells. The inner part of medulla consisted of polyhedral cells, small in size and stained less eosinophilic than the outer cells.It considered nor adrenaline secreting cells. The nor-adrenaline cells contain bigger irregularly shaped electron-dense, oval granules with an intensely electron-dense core.