Abstract: The possibility of the antioxidant action of Sacoglottis gabonensis stem bark extract and its isolate, bergenin in peroxidative deterioration of three local vegetable oils, groundnut palm and soya bean was examined. The lipid hydroperoxide, malondialdehyde and malonaldehyde contents of the vegetable oils were determined before and after 30 days storage/incubation with bark extract or bergenin. Treatment of stored vegetable oils (palm oil and soya bean) with bark extract significantly reduced the level of peroxidative deterioration (P<0.05) during storage compared with the bark extract free controls. Bergenin exhibited similar properties to a lesser extent. So, bergenin appears to be the phytochemical constituent that is largely responsible for the antioxidant property of the extract. The antioxidant properties of the bark extract and its isolate bergenin may find ready application as antioxidant additives in foods, beverage and pharmaceutical industries.