This work was carried out on the cloacal bursa from 60 apparently healthy geese and pigeons of both sexes at 2 weeks, 2 months, 6 months, 1 year and 2 years of age. The specimens were collected and examined anatomically and histologically after being fixed in 10% buffered neutral formalin. The specimens were subjected to processing till paraffin sections were obtained and stained with; Hematoxylin and Eosin, Alcian blue, Periodic Acid-Schiff, Alcian blue / Periodic acid-shiff combination, Van Gieson, Crossmon`s trichrome and Weigert`s elastic stain. Macroscopically, the cloacal bursa was located on the dorsum of the cloaca and connected with it by stalk. The cloacal bursa was pale pink in colour, fleshy in consistency. It was elongated sac-like in geese and oval sac-like in pigeons. The mucosa of the cloacal bursa was characterized by the presence of 13 plicae that organized as alternated tall and short ones in longitudinal section. The plicae extending from the dorsal wall was mainly short and the tallest one extending from the ventral wall with cross section in geese. Meanwhile in pigeons had extensive interdigitating folding. The CB was still present until 2 years aged geese while disappeared at 6 months aged pigeons. Histologically, the wall of the CB was composed of three tunicae, a tunica mucosa, a tunica musculosa and a tunica serosa. In geese, the mucosa was distributed into plicae and deep crypts. The plicae shapes were leaf-like in ages of 2 weeks and 2 months of both sexes and 6 months females with irregular lumen of starfish-like. The plicae surface epithelium was IFE of pseudostratified type, FAE of cuboidal cells with cushion-like of polyhedral cells and marginal stratified epith. inbetween. The subepithelium structures composed of stromal C.T. of vertical thick central strand and branched thin interfollicular strand among follicles.Each bursal follicle was composed of a peripheral dark cortex and a central paler medulla with demarcated line of CMB. The follicular cortex was composed of lymphocytes of different sizes, scattered cortical reticular cells and blood capillaries. The paler medulla contained lymphocytes,lymphoblasts , bursal secretory dendritic cells and numerous medullary reticular cells. The tunica muscularis was composed of inner interrupted longitudinal and outer continuous circular layer of smooth muscle fibers. With progress of ages particularly in males, the plicae decreased in height, thickness and numbers with prominent lumen. At female of 6 months age, early appearance of microscopic involution signs was observed as epithelium infolding, pyknotic nuclei among FAE and deeply acidophilic of medullary reticular cytoplasmic processes. Meanwhile, in males, metaplasia started at bursal stalk, different stages of follicular degeneration with cyst formation and subepithelium fibrosis that occupied approximately one-third to one-half of the mucosa. Also, there were thickening of tunica muscularis. At female of one year of age, the plicae were more decreased in number, height and thickness with clear lumen. The number of FAE areas were decreased, bursal follicles decreased in numbers and sizes with follicular changes as paler medulla, lymphocytes depletion, reticular cells degeneration, cyst formation, atrophied follicles and thickening of C.T. core, interfollicular C.T. of plicae and tunica muscularis. Meanwhile, in 1 year male geese, lumen was wider and H-shape. Two main indented wide,blunt thump-like plicae plus two short low branched plicae. C.T. core of plicae and tunica muscularis were greater than 1-year aged female.FAE disappeared with the presence of focus of thin mucosa. Atrophied follicles became in groups. With advanced ages, the involution signs were more obvious. The cloacal bursa of 2-year-old became with thick muscular wall and thin mucosal layer, distributed into finger-like projection with tapered or blunt end and some with branched free end in female. Meanwhile, in male, mucosa thicker than female, plicae were tongue-shape and lumen distributed in-between The plicae cores were dense collagenic fibers and extending smooth muscles fibers from tunica muscularis with absence of normal follicles & covering FAE. Besides, solid epithelial nest appeared in male and advanced thickening of tunica muscularis of both sexes. With involution, the three tunicae were changed and more prominent progressive changes had occurred in subepithelium. In pigeons, the CB of 2 weeks age, had extensive interdigitating folding with luminal crypts. The surface epithelium was distinguished into IFE of simple cuboidal cells and FAE. The subepithelium composed of tightly adjoining polygonal bursal follicles that were separated from each other by delicate and thin interfollicular C.T of mainly collagenic fibers. The bursal follicles were divided into cortical and medullary parts by ill-distinct CMB of cortical blood capillaries and epithelial cells. Cortex was composed of lymphocytes and cortical reticular cells. The medullary part was composed of small lymphocytes, lymphoblast, BSDCs and medullary reticular cells. The tunica muscularis consisted of one layer of circular smooth muscle fibers. In 2-month-old, the walls become thicker than those of the previous age. Involution signs were detected in males than females. The lined epithelium was simple columnar in females and progressively flattened in males. Also, there were degenerated medullary reticular cells that latter forming hyalinized foci with prescence of pyknotic nuclei in the bursal follicles. Tunica muscularis composed of I.L. and O.C. smooth muscle fibers. With advanced age, the cloacal bursa was disappeared and remained as lymphoglandular tissue at 6 months old and areas of stratified cuboidal and secretory cuboidal cells that enveloped by a smooth muscle and C.T. capsule at 2-years- old.