The antidepressant effects of the flavonoid-rich fraction of Monodora tenuifolia seed extract were examined by assessing the extent of attenuation of behavioural alterations and oxidative damage in the rats that were stressed by forced swim test. Compared with the model control group, the altered behavioural parameters were attenuated significantly(P < 0.05) in the group treated with the flavonoid-rich fraction(100 and 200 mg·kg-1), comparable to the group treated with the standard drug, fluoxetine(10 mg·kg-1). The flavonoid-rich fraction and fluoxetine improved significantly(P < 0.05) the activities of the antioxidant enzymes such as superoxide dismutase and catalase as well as other biochemical parameters such as reduced glutathione, protein, and nitrite in the brain of the stressed rats. These results suggested that the flavonoid-rich fraction of Monodora tenuifolia seed extract exerted the antidepressant-like effects which could be useful in the management of stress induced disease. The antidepressant effects of the flavonoid-rich fraction of Monodora tenuifolia seed extract were examined by assessing the extent of attenuation of behavioral alterations and oxidative damage in the rats that were stressed by forced swim test. Compared with the model control group, the altered behavioral parameters were attenuated significantly (P <0.05) in the group treated with the flavonoid-rich fraction (100 and 200 mg · kg -1), comparable to the group treated with the standard drug, fluoxetine (10 mg · kg -1). flavonoid-rich fraction and fluoxetine improved significantly (P <0.05) the activities of the antioxidant enzymes such as superoxide dismutase and catalase as well as other biochemical parameters such as reduced glutathione, protein, and nitrite in the brain of the stressed rats. These results suggested that the flavonoid-rich fraction of Monodora tenuifolia seed extract exerted the antidepressant-like effects which could be useful in the management of stress induced disea se.