Diabetes mellitus is a common endocrine disorder. Anti-diabetic agents from natural and synthetic sources are available for the treatment of this disease. Berberis integerrima is a medicinal shrub used in conventional therapy for a number of diseases. The aim of the present study was to investigate the effects of aqueous extract of Berberis integerrima root (AEBI) on some physiological parameters in normal and streptozotocin-induced (STZ-induced) diabetic male Wistar rats. STZ-induced diabetic rats showed significant increases in the levels of blood glucose, triglycerides (TG), total cholesterol (TC), low density lipoprotein LDL-cholesterol (LDL-C), creatinine (Cr), urea, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin while body weight, high density lipoprotein HDL-cholesterol (HDL-C) and total protein levels were significantly decreased compared to normal rats. Treatment of diabetic rats with different doses of aqueous extract of Berberis integerrima root (250 and 500 mg/Kg bw) resulted in a significant decrease in blood glucose, triglycerides, cholesterol, LDL-cholesterol, ALT, AST, ALP, total bilirubin, creatinine and urea while HDL-cholesterol and total protein levels were markedly increased after six weeks compared to untreated diabetic rats. The effects of the AEBI at dose of 500 mg/Kg in all parameters except blood glucose (similar) is more than to the standard drug, glibenclamide (0.6 mg/Kg, p.o.). The results of this study indicate that the tested aqueous extract of Berberis integerrima root possesses hypoglycemic, hypolipidemic and antioxidant effects in STZ-induced diabetic rats.