Introduction: The World Health Organization (WHO) has estimated that about 80% of the world’s population rely mostly on traditional medicine. Peptic ulcer disease (PUD) which results from an imbalance between stomach acid-pepsin and mucosal defense barriers is a chronic disease affecting up to 10% of the world’s population and represents 33% of gastroenterology consultations in Cameroon. The people in low medium incomecountries depend mostly on medicinal plants for primary healthcare since they can be accessed quickly and are affordable. Such plant is Ficus thonningii Blume, which is found abundantly in Africa and also in Cameroon. The objective of this study was to phytochemically screened the aqueous fruits extract of Ficus thonningii (AEFFt), and investigate their antiulcer activity. Methods: The aqueous fruits extract was phytochemically screened following standard qualitative methods. Four in vitro tests to characterize antacid properties were carried out. Ulcers were induced using an ethanol and hydrochloric acid (HCl/EtOH) solution. Ulcer preventive (anti-ulcer) activity was investigated in 6 different treatment groups: 2 conventional drugs (Maalox 100 mg/kg, Omeprazole 20 mg/kg), three doses of AEFFt at (125 mg/kg, 250 mg/kg, & 500 mg/Kg), and a vehicle treatment group (administered only the ulcerogenic agent). Histological analysis of the stomachs was carried out. Results: The phytochemical screening of the aqueous extract of fruits of F. thonningii showed the presence of flavonoids, mucilages, saponins, gallic tannins, betacyanins, and total polyphenols. Following the in vitro tests, we obtained a value of 7.4mEq for acid neutralization capacity (ANC) for the extract, and a pH of 4.2 for the extract following FDA test. For the in vivo tests, the aqueous extract of fruits of F. thonningii (AEFFt) showed a dose-dependent increase ulcer-preventive (gastroprotective) activity with the three treatment aqueous extracts doses. Conclusion: The study showed that, the aqueous extract of fruits of Ficus thonningii showed a dose-dependent ulcer-preventive activity that could be accounted for by the presence of bioactive phytochemicals like polyphenols (flavonoids, tannins).