Rats that were given an intraperitoneal injection of gold thioglucose (GTG, 0.3 mg/g) developed hemorrhagic lesions in the gastric mucosa 24 hours after the injection. The gastric juice volume and the generation of acid and pepsin were significantly increased 24 hours after the GTG injection (p < 0.01). Simultaneous administration of famotidine (3 mg/kg) with GTG significantly reduced gastric juice secretion and the generation of acid and pepsin (all p < 0.01), as well as suppressing the development of hemorrhagic lesions. These results indicate that there is a relationship between the hemorrhagic lesions induced by GTG and increased acid and pepsin generation. Rats treated with GTG seem to be a useful new animal model for the investigation of pepsin secretion.