Osmoregulation is one of the most important factors determine the presence of vertebrates in its habitat. The renal morphology, histology and ultrastructure of two species of the family Ardeidae, Cattle egret (Bubulcus ibis) as a terrestrial bird (from Nahia and Mansurya) and Squacco heron (Ardeolaralloides) as aquatic bird (from Manzala lake) were examined. The results were obviously varied, the Cattle egret from Nahia in comparing with the Cattle egret from Mansurya have a few number of reptilian-type nephrons, numerous mammalian- type nephrons. The renal corpuscles have narrowest filtration slits. On the other hand, the Squacco heron showed numerous reptilian-type nephrons, a few number of mammalian-type nephrons, the renal corpuscle has numerous and widest filtration slits and thin basal lamina to increase the filtration surface area. Results illustrated the ability of the Cattle egret to adapt to its terrestrial environment, as these characteristics limit the glomerular filtration rate. On the contrary, the Squacco heron well adapted to its aquatic environment by increasing the glomerular filtration rate.