Objective: The aim of the present study was to evaluate the possible antidiabetic effects of Amaranthus spinosus leaf extract (ASEt) against streptozotocin-nicotinamide induced diabetes &oxidative stress in albino rats.Methods: Experimental diabetes was induced by a single dose of STZ (60 mg/kg) administered by intraperitoneal way after the administration of nicotinamide (120mg/kg). The oxidative stress was measured by reduced glutathione (GSH) content and by enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in liver and kidney. Biochemical observations were further substantiated with histological examination of pancreas, kidney and liver. Results: The increase in blood glucose with the decrease in GSH content and in enzymatic activities were the salient features observed in diabetic rats. Administration of ASEt (250 & 500 mg/kg bw/day, i.p) for 21 days caused a significant reduction in blood glucose in STZ-nicotinamide treated rats when compared with diabetic rats. Furthermore, diabetic rats treated with ASEt leaf extract showed a significant increase in the activities of both enzymatic and non-enzymatic antioxidants when compared to those of diabetic rats. Degenerative changes of pancreatic cells in STZ treated rats were minimized to near normal morphology by administration of ASEt leaf extract as evidenced by histopathological examination.Conclusion: Results clearly indicate that Amaranthusspinosus treatment attenuate hyperglycemia by decreasing oxidative stress and pancreatic cells damage which may be attributed to its antioxidative potential.