The aqueous extract of Ageratum conyzoides leaves was evaluation for their cytoprotective activity against ethanol-induced gastric lesions in rats. Four groups of male Sprague Dawley rats each consist of 6 animals. Group I animals were pretreated with phosphate buffer saline 5 mL kg 1 as a control, where as Group II and Group III rats were pretreated with 250 mg kg 1 and 500 mg kg 1 Ageratum conyzoides extract (5 mL kg 1), respectively. Group IV rats were pretreated with cimetidine 50 mg kg 1 as reference. After 30 min all animals were administered absolute ethanol 5 mL kg 1 orally and 15 min later all rats were sacrificed. Macroscopically, oral administration of absolute ethanol to rats pretreated with PBS significantly produced extensive hemorrhagic lesions of gastric mucosa, whereas animals pretreated with 250 mg kg 1 and 500 mg kg 1 aqueous extract or cimetidine significantly reduced the formation of gastric lesions compared to control group. Microscopically, pretreated rats with aqueous extract or cimetidine showed significantly marked inhibition of gastric lesions and marked reduction of submucosal edema compared to control group. These results strongly document the beneficial cytoprotective effects of plant extract against ethanol-induced gastric ulcer in rats.