The aqueous extract of whole plant of Coronopus didymus LINN (CD) [Family: Bracicacea] was screened for antiallergic, antipyretic and hepatoprotective effects in rats and hypoglycemic activity in mice. The extract showed significant antiallergic, antipyretic, hypoglycemic and hepatoprotective activity at 200 and 400 mg/kg doses on oral administration. Mechanistically, CD acts as an antioxidant as evidenced by its ability to scavenge DPPH and superoxide radicals. All the observed activities may be due to the presence of flavonoids, saponins and tannins as they are reported to possess a variety of biological activities. © 2005 Pharmaceutical Society of Japan.