摘要Objective: The use of herbs in treatment of diseases is gradually becoming universally accepted especially in non industrialized societies. Citrullus lanatus Thunb (Cucurbitaceae) commonly called water melon is widely consumed in this part of the world as food and medicine. This work was conducted to investigate the phytochemical composition, proximate and metal content analysis of the seed of Citrullus lanatus and to determine the antiulcer action of the methanol seed extract. Methods: Phytochemical screening, proximate and metal content analysis was done using the standard procedures and the antiulcer activity was evaluated against acetylsalicylic acid-induced ulcers. Results: The results revealed the presence of the following phytochemicals;flavonoids, saponins, tannins, alkaloids, glycosides. Proximate analysis indicated high concentration of carbohydrate, protein and fat while metal analysis showed the presence of sodium, calcium, zinc, magnesium at levels within the recommended dietary intake. Antiulcer potential of the extract against acetylsalicylic acid induced ulceration of gastric mucosa of Wister rats was evaluated at three doses (200mg/kg, 400mg/kg, and 800mg/kg). The ulcer parameters investigated included ulcer number, ulcer severity, ulcer index and percentage ulcer protection. The antiulcer activity was compared against ranitidine at 20mg/kg. The extract exhibited a dose related antiulcer activity with maximum activity at 800mg/kg (P<0.001). Conclusions: Proximate and metal content analysis of the seeds provides information that the consumption of the seeds ofCitrullus lanatus is safe. This present study also provides preliminary data for the first time that the seeds of Citrullus lanatus possesses antiulcer activity in animal model.