The use of medicinal plants in diseases is as old as man. The World Health Organization (WHO) has long recognized and drawn the attention of many countries to the ever increasing interest of the public in the use of medicinal plants and their products in the treatment of various ailments. Peptic ulcer is a common global health problem with increasing incidence and prevalence. Plant based medicines are now considered as an alternative approach to control. The present research was carried out to investigate the extract of the rind of Citrullus lanatus for ameliorative effects in aspirin induced gastric ulceration in rats. Thirty (30) male rats weighing between 180g and 250g were used for this study. The rats were randomly divided into five groups: Groups 1 to 5. Gastric ulceration was induced in all the rats by using 0.2gm/kg of aspirin orally. The rats were subsequently treated as follows: Group 1 served as the control (received 2ml/kg bw of vehicle), Groups 2, 3 and 4 received 100mg/kg, 200mg/kg and 500mg/kg bw of the methanolic extract of the rind of Citrullus lanatus respectively, while Group 5 received 200mg/kg bw of Cimetidine. Treatment was done for 21days. On day 22, gastric juice volume, gastric acidity, ulcer index, gastric pH and percentage ulcer inhibitions were determined. Results obtained showed that, compared to control rats, administration of the methanolic extract of the rind of Citrullus lanatus protected the gastric mucosa against aspirin effect by significantly reducing the gastric juice volume, gastric acidity, and ulcer index (p<0.05) in a dose dependent manner while the gastric pH (p<0.05) and the percentage ulcer inhibition were significantly increased (p<0.05) in rats treated with the extract when compared with the control and the effect is similar to that of rats treated with Cimetidine. Activities of Super oxide dismutase (SOD) and Catalase were significantly increased (p<0.05) while Malondialdehyde (MDA) was significantly decreased (p< 0.05) in high extract dose treated rats when compared with the control. This study shows that the extract possess curative effect against aspirin induced gastric ulceration in male wistar rats. The findings suggest that the methanolic extract of the rind of Citrullus lanatus exerts a possible beneficial ameliorative effect on the stomach of the male albino wistar rats exposed to aspirin ulceration.