Rainbow watersnake is a snake that can be found in ponds, has a relatively medium body, a maximum length of 80 cm, generally between 50-60 cm, small-headed, a rather large belly, and short-tailed. The aim of this study is to determine the structure of the histology of the lungs of watersnake (Enhydris enhydris). This study used a sample of 3 watersnakes (Enhydris enhydris) with a body length of ± 50 cm. This study conducted a micro technical method with hematoxylin-eosin (HE) staining. Data obtained from the results of this study were analyzed descriptively and presented in the form of images. Macroscopic observations of the warp in snakes are long, most of the trachea attaches to the warp, and there are water sacs or swimming pouches at the tip of the warp, as well as the histological features of the snakes' warp, alveolar ducts, alveolar sac and alveoli, the histological structure of the lungs in watersnakes (Enhydris enhydris) consist of type 1 alveoli epithelial cells, type 2 alveoli cells, muscle bundles, connective tissue, capillary vessels, and macrophage cells. Based on the results of the study, it can be concluded that the histological structure of the watersnake (Enhydris enhydris) lung is different from the histological structure of the reptile function in general. In the lungs of watersnakes (Enhydris enhydris) only consists of alveolar ducts, alveolar sacs, alveoli, and the presence of water sacs at the ends of the lungs.