The aim of this study was to investigate the antidiabetic, antihyperlipidemic and antioxidant activities of methanolic extract of whole plant of Amaranthus viridis (MEAV) in alloxan (ALX) induced diabetic rats. Diabetes was confirmed after 5 days of single intraperitoneal injection of ALX (140 mg/kg) in albino Wister rats. MEAV (200 and 400 mg/kg) and glibenclamide (10 mg/kg, p.o.) orally administered daily for 15 days, blood was withdrawn for glucose determination on 0, 1, 10 and 15 days respectively. On the 15th day, overnight fasted rats were sacrificed and blood was collected for the determination of high density lipoproteins cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), total cholesterol (TC), total glycerides (TG) and total proteins (TP). For in vivo antioxidant activity of MEAV, liver tissues were homogenized and the assay of lipid peroxidation and was measured as Malondialdehyde (MDA), glutathione (GSH), catalase (CAT) and total thiols (TT) were performed in control, ALX and MEAV treated rats. MEAV at doses of 200 and 400 mg/kg showed significant reduction is blood glucose, lipid profiles and significant improvement in MDA, GSH, CAT and TT when compared to diabetic control group. In vitro α-amylase inhibition activity of MEAV was also studied. We concluded that MEAV possess antidiabetic, antihyperlipidemic and antioxidant activities.