Reserpine, serotonin, and histamine as well as stress were employed to produce dystrophic lesions in the gastric mucosa of rats. Analysis of stomach tissues revealed that agencies which reduced catecholamine concentration also decreased endogenous levels of pepsinogen. Concentrations of the zymogen were increased after parenteral administration of dopa, but were not changed by injections of α-methyl-dopa. The evidence supports the suggestion that catecholamines participate in the control of pepsin production and are involved in the secretory function of the stomach.