This protocol is for injection of neural tracers into the wall of the stomach to identify neurons innervating various tissues in the gastric wall including the gastric mucosa and the gastric muscle/myenteric plexus. This includes extrinsic neurons such as vagal efferent and afferent neurons, sympathetic and sensory neurons, as well as intrinsic neurons in the enteric plexuses, both locally and within other parts of the digestive tract, for instance the duodenum. It utilises tracer substances that are known to be taken up by the endings of neurons, including fast blue, which is taken up very efficiently by axons, but also fluorescent microspheres whose diffusion within tissues is limited so that they can be localized to particular tissues.