SUMMARY1. A rhomboencephalic reflex loop involved in the gastrosecretory-effect of functional cytoglucopoenia caused by 2-deoxy-D-glucose (2-DG) was investigated in thirty-five cats prepared with chronic gastric fistulae.2. Injection of 60 mg 2-DG/kg in the vertebral artery of cats subjected to acute electrolytic transaction of the pontomedullary transition produced gastric secretion.3. Microinjection of 2-DG in the medial and in the lateral components of the nuclei of the solitary tract elicited an intense gastric secretion. Sites at the level of the obex were more effective than the caudalmost portions of the nuclei in causing the secretary effect. Microinjection of saline in the same nuclei was totally ineffective whereas both saline and 2-DG solutions induced secretion when microinjected in the dorsal nuclei of the vagus. The gastrosecretory effect of microinjection of saline and 2-DG in the dorsal nuclei of the vagus is ascribed to mechanical stimulation of the effector parasympathetic neurones that innervate gastric mucosa.4. It is concluded that rhomboencephalic neurones sensitive to functional cytoglucopoenia are located in the nuclei of the solitary tract. Activation of these neurones conveys to effector neurones information that triggers gastric secretion.