This chapter reviews the canine olfactory system, and the basics of the anatomy and physiology of scent perception in the dog. The olfactory system is basically the same in humans and dogs, but there are obviously some differences that allow dogs to do what they do. The goal is to get air that contains odor chemicals to the cells that detect it and then send the message to the brain where that input is processed. The basic parts of the olfactory system are the nostrils, nasal turbinates, olfactory sensory cells, olfactory nerves, and the brain. Once air passes into the nostrils, it moves through the nasal turbinates, a highly coiled pathway surrounded by bone. The coiled formation of the turbinates creates a large surface area with an extensive blood supply. Olfactory sensory cells are actually chemoreceptors—a type of nerve cell that is specially designed to interact with chemicals.