The activity of dexamethasone and taxifolin {(2R, 3R)-2-(3, 4-Dihydroxyphenyl)-3,5,7-trihydroxy-2,3-dihydrochromen-4-one}supplementation on prostaglandin E2 and thromboxane A2 in gastric acid secretion and anti-ulcer was studied. Twenty male Wistar rats (180g-200g body weight) were used. The rats were randomly selected into four groups containing 5 rats each. Group 1 was the control group fed on normal rat feed. Group 2 received 3mg/kg of Dexamethasone (intraperitoneally) at one day interval. Group 3 received 3mg/kg of Dex. intraperitoneally and 1mg/kg body weight of taxifolin orally while group 4 received 1mg/kg body weight of taxifolin. At the end of 6 weeks, basal and peak gastric acid output was measured by continuous perfusion of rats stomach under anaesthesia with normal saline at the rate of 1ml/min. Gastric acid, mucus secretion, ulcer index, PGE-2 and thromboxane A2 activity were determined according to standard procedures. Results showed a significantly (p<.05) decreased prostaglandin and mucus secretion level and a raised thromboxane concentrations and gastric acid output in dexamethasone administration. Taxifolin significantly (p<.05) lowered thromboxane A2 concentration in Dex treatment while increasing the prostaglandin E2 level. We conclude that Taxifolin decreases dexamethasone- induced gastric acid secretion, increases prostaglandin activity but reduces thromboxane concentration.