Objective: Coscinium fenestratum belongs to the family of Menispermaceae. It is a woody plant that originated from Indomalaya regions such as southern India, Sri Lanka, Thailand, Vietnam, Cambodia, and West Malaysia. C. fenestratum has been reported to possess various pharmacological actions such as antioxidant, antiproliferative, antidiabetic, and antibacterial activities. In addition, this medicinal plant has also been used to treat gastrointestinal disorders, including ulcer. The purified fractions A-E of dichloromethane (DCM) extract obtained from the stem of C. fenestratum were investigated for antioxidant activity and its ability to protect the gastric mucosa against hydrochloric acid (HCl)/ethanol, nonsteroidal anti-inflammatory drugs (NSAIDs), and stress-induced ulcer. The bioactive compounds were identified using high-performance liquid chromatography (HPLC) and simple biochemical screening. Methods: Air-dried stem extract was soaked in DCM to obtain crude extract which was purified using column chromatography. HPLC and basic biochemical screening were used to identify the bioactive compound present. HCl/ethanol induced, NSAIDs, and stress of animal were used to induce gastric ulcer. The rats were orally administered with purified A-E extract for gastroprotective and antioxidant activity. Results: The oral administration of fractions A-E exhibited gastroprotective activity by reducing the ulcerative index induced by HCl/ethanol, NSAIDs, and stress compared to saline. The extract showed high antioxidant effect, especially fraction E. The HPLC and phytochemical analysis of fraction E showed the presence of palmatine and flavonoid. Conclusion: The extract showed a very strong gastroprotective and antioxidant activities and the highest activity was observed by fraction E. The activity may be because of the presence of palmatine and flavonoid.