A review of this research compared the histology of the organ systems of marine mammals, primarily bottlenose dolphin with the microscopic structure of domestic animals. The stomach is complexed and consists of forestomach, pyloric, and fundic part. A significant feature of the respiratory system is the large amount of elastic tissue, which provides a much more intensive exchange of air, and exploits a much greater amount of inhaled oxygen up to 90%. Urinary System of the bottlenose dolphin is characterized by highly lobulated kidney where each slice is a separate kidney, renculus. White body of the ovary of the bottlenose dolphin, and other marine mammals, never completely disappears. One of the main specifics of the male reproductive system established at the striped dolphin, but not in the bottlenose dolphin, and it is the seasonality of mating. In addition, studies have shown that in both types of dolphins cavernose body of penis less developed and connected in one mass. Penis belongs fibroelastic type, which we find in pigs and ruminants. The nervous system is characterized by considerably less developed dorsal root (sensory) in relation to the ventral (motor) horn spinal cord. Partially, in the bottlenose dolphin is harder to make all layers of the cerebral cortex, but they are present, and has all typical layers of the cortex as well as in domestic animals. Pituitary differs from that of terrestrial mammals to their shape and arrangement of typical parts. The aorta has a much thicker wall than aorta domestic animals with many elastic lamellae, and the Purkinje fibers of the heart are located closer to the endocardium for the protection of these fibers from pressure changes. Lymph nodes of bottlenose dolphins have not a distinct cortex and medulla, and lymph nodes of these types are present all over the body. Leather of the bottlenose dolphin has extremely thick epithelium with protective parakeratin layer. Marine mammals has its morphology well adapted to living conditions in water as a result of which there have been some changes in the macroscopic and microscopic structure of individual organs and organ systems, although the basic scheme of the microscopic structure corresponds to that in mammals in general.