This study aimed to develop an experimental animal model of duodenal ulcer for application to nutrition, and to verify the nutritional characteristics. The 7 different doses and 8 different injections of cysteamine and 2 kinds of diets with different casein levels(10%, 20%) were tested to examine the incidence and the process of duodenal ulcer in female Sprague-Dawley rats. The result showed that the duodenal ulcer was induced when rats fed 10% casein diet(for 9 days) were injected 6 times with 13mg/100g BW cysteamine. The first injection was conducted after 24 hours of fasting, followed by the 2nd shot after 3 hours. The following shots were repeated every 3 day(4th and 7th days). Duodenal ulcer was observed 3 days after the last injection by optical microscope and the naked eye. The characteristics of nitrogen bioavailability of duodenal ulcer model were as followings : 1) gastric emptying rate was faster, 2) trypsin activity at duodenum was higher, 3) total protein concentration at serum and nitrogen retention rate were lower than the control. (Korean J Community Nutrition 1(2) : 260-268, 1996)