Cupressus sempervirens (C. sempervirens) belongs to the family Cupressaceae. It is widspread in Northern Africa, Greece, Turkey, North America, Cyprus and Syria. Cupressuflavone is the major ingredient of the plant leave extract. The aim of the present study was to evaluate the antiulcerogenic activity of the extract of C. sempervirens leaves in gastric ulcer tissues induced by indomethacin. The results of the present study revealed that indomethacin significantly decreased glutathione S-transferase (GST), glutathione peroxidase (GPx), catalase (CAT), reduced glutathione (GSH), glutathione reductase (GR) and superoxide dismutase (SOD) levels, while it increased significantly lipid peroxidation (MDA), nitric oxide (NO) and protein carbonyl (PC) levels in gastric tissue. Furthermore, indomethacin decreased p53 expression, while it increased bcl-2 expression in gastric tissue. Pretreatment with 5%, 10% & 20% of the LD50 of C. sempervirens and cupressuflavone of indomethacin-treated rats restored all the above parameters to approach normal values. C. sempervirens at the highest dose was more effective than the two lower doses. C. sempervirens proved more potent than cupressuflavone. In conclusion, C. sempervirens exerted antiulcerogenic activity and the effect was dose-dependent and related to the cupressuflavone ingredient of the plant leave extract.