This masterclass lecture will cover the normal anatomy of several amphibian and reptilian species common as pets, in research colonies, and as wildlife patients. Comparisons will be made to provide understanding of what is known from the peer-reviewed literature. The renal system and ducts, urinary bladder, if present, and cloaca will be illustrated. Nephron form and function will be discussed in the context of the species' physiological ecology, particularly if with regard to the intermediate segment length. The functional difference in urinary tracts of amphibians and reptiles will be described in the context of their mechanisms for eliminating nitrogenous wastes. This lecture will provide the foundations for the clinical and pathology lectures which will follow.