Background: There is extensive variety of chemical compounds with antiulcer activity, which are isolated from medicinal plants. Matricaria chamomilla or Matricaria recutita or German chamomile, also spelled chamomile (MC), is one of the most widely used medicinal plants. In the present study, the extract of MC flowers was evaluated for antiulcerogenic activity and acute toxicity profile. Methods: To evaluate antiulcer effect of MC extract, 15 female bulb-c mice were divided into three groups (five mice in each group). The first and second groups received 400 mg/kg sucralfate and 400 mg/kg MC extract respectively by the intragastric route. The control group received 1.0 ml distilled water. After 30 min, gastric ulceration was induced by oral administration of 1.0 ml of a 0.3 M solution of HCl in 60% ethanol in all animals. One hour later, the area of the gastric lesions and hemorrhage was measured by stereological method. To evaluate the toxicity of MC extract, 10 male and 10 female mice were divided into control and experimental groups (5 mice in each group). The experimental and control groups received by the intragastric route a single dose of 5000 mg/kg MC extract and water respectively. After 14 days the mice’s liver, kidneys, lung, and heart were examined macroscopically and the relative weights (organ/body) were determined. Statistical comparisons between the groups were performed by Mann-Whitney U test. Results: Oral administration of MC extract at 400 mg/kg can be effective in preventing gastric ulceration in mice and does not produce toxic effects in doses up to 5000 mg/kg. Conclusion: Matricaria chamomilla can prevent experimental gastric ulcer in mice.