Boerhaavia diffusa, a green leafy vegetable and medicinal plant as whole was traditionally used in treating different ailments due to its multiple pharmacological activities viz., immuno suppressant, anti-diabetic, analgesic, hepatoprotective, antiviral and antifibrinolytic activity, etc. The therapeutic importance of plants is mainly due to polyphenols and their antioxidant properties. In the present study, the antioxidant potency of methanolic extract of B. diffusa (BDE) was investigated using various in vitro model systems such as DPPH, superoxide, nitric oxide radical, hydroxyl radical scavenging, reducing power and iron chelating activity. Antiperoxidative activity of B. diffusa was also studied in linoelic acid emulsion system. BDE showed significant scavenging activity against hydroxyl and superoxide radical. It also significantly inhibited the lipid peroxidation in linoleic acid emulsion system. Multiple antioxidant activity of BDE was also evident from its significant reducing power and ferrous ion chelating potency. The data obtained in the in vitro models clearly establish the antioxidant potency of BDE.