The aim of the present study was to assess the antihyperglycemic and antioxidant activites of the methanol extracts of Amaranthus polygamus (MEAP). Indian folklore suggests the plant as good liver tonic and is recommended as vegetable for diabetic and anemic patients. MEAP was evaluated for antidiabetic activity by using streptozotocin (STZ)- induced diabetic rats. The administration of MEAP and glibenclamide (GLB) to diabetic rats for 21 days showed marked fall in serum glucose (SG) levels compared to basal values i.e. at 1st day. MEAP (400 mg/kg) and GLB (0.5 mg/kg) showed significant reduction(P<0.0001) in SG level (37.2% and 52.9%, respectively). MEAP (400 mg/kg) and GLB showed significant improvement in oral glucose tolerance test (OGTT) and slight elevation in SG level, but after 60 min it showed marked downfall over the period of 120 min in comparison with 30 min. MEAP also possesses some antioxidant activity IC50 = 47.80 μg/ml in DPPH assay.