Imbalance between exogenous damaging agents and protective factors in the gastro-duodenum tract can lead to peptic ulcer disease. Herbal medicines could be an effective treatment to human gastric ulcers. This study aimed to investigate the protective effect of AGAR-HP hard capsules on cysteamine-induced gastric-duodenal ulcers in experimental rats. The animals were divided into five treatment groups: Group 1 (control) and group 2 (model) were treated with distilled water, group 3 received esomeprazole at 10 mg/kg, group 4 received AGAR-HP at 0.074 g/kg, and group 5 received AGAR-HP at 0.221 g/kg. All the rats were treated for seven consecutive days. On day 7, peptic-duodenal ulcer were induced by oral cysteamine 400 mg/kg. The number of rats with the ulcer, the number of ulcers per rat, and the ulcer index of each group were recorded. Compared to group 2, AGAR-HP at high dose reduced the mean number of ulcers and the ulcer index under macroscopic and microscopic examinations. These parameters also decreased in the group of AGAR-HP low doses compared to the cysteamine control group. AGAR-HP hard capsules showed some protective effect on cysteamine-induced gastric ulcers in experimental rats.