The Antidiabetic activity of Monochoria vaginalis presl. (Family: pontederiaceae) was investigated inAlloxan induced diabetic albino rats. The Monochoria vaginalis prel plant has been reported for itsanalgesic activity, nephrotoxic, antioxidant activities and nutritive values, paniya tribe of India used theleaves for diabetes15 but there are no scientific data is available regarding the effect on the blood glucoselevels. So we have made an attempt to use hydroalcoholic extract of Monochoria vaginalis presl leaf(HAEMV) for studying anti-diabetic activity. The dried leaves of Monochoria vaginalis presl. weresubjected to extraction by continuous hot percolation using water and ethanol (50 : 50) as solvent andwere subjected to standardization using pharmacognostical and phytochemical screening. Dose selectionwas made on the basis of acute oral toxicity study (200 mg/kg body weight) as per OECD and CPCSEAguidelines. Oral administration of extracts of Monochoria vaginalis presl (200mg/kg, 400mg/kg) for 14days resulted in a significant reduction in blood glucose levels. The extract also prevented body weightloss in diabetic rats.