The present study was carried out to investigate the effects of iodoacetamide on gastric acid secretion and dye binding mucoprotein in rats. The result were obtained as follows: 1) Iodoacetamide group was not noted significant difference in the volume of gastric juice compared with that of control group. 2) The pH was 6.2+-0.4 in iodoacetamide group and 4.7+-0.8 in control group. Its level vas ignificantly increased in iodoacetamide group (p<0.05). 3) The titratable gastric acid output in iodoacetamide group (5.7+-2.6 mEq/L) was significantly lower than control group (12.9+-5.1mEq/L) (p<0. 001). 4) The Alcian blue binding capacity of gastric juice was 51.6+-21.8 dye-binding mg/dl in iodoacetamide group and 39.7+-52.1 dye-binding mg/dl in control group, showing significantly increased in iodoacetamide group (p<0.05).