Oxidative stress is involved in both pathogenesis and complications of diabetes . The need to identify agents with a potential for preventing such damage and complication has assumed great importance. In the present study , the effect of chronic oral administration of raw garlic homogenate on oxidative stress and tissue injury was studied in kidney and liver of Streptozotocin (STZ)-induced diabetic rats. METHODS: male albino rats of wistar strain weighing 180-200 g were used. Rats were divided into four groups 6 rats each. Group 1 : Is a control group in which rats were received only 0.5 ml of vehicle (citrate buffer pH 4.5) . Group II: In which rats were treated orally with raw garlic homogenate (500 mg/kg b.w./ once /day) 20% homogenate in distilled water for 30 days.Group III : Rats were treated only with STZ 0.5ml (60mg/kg single intraperitoneal (i.p.) dose) 2.4% solution in citrate buffer . Group IV : Rats were treated with .5ml STZ (60mg/kg single i.p. dose) 2.4% solution in citrate buffer plus raw garlic homogenate orally (500 mg/kg b.w./ once /day) 20% homogenate in distilled water for 30 days. Blood aliquots were collected for serum separation. Serum was used for determination of serum levels of glucose, aspartate aminotransferase(AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, urea and creatinine as well as total cholesterol, LDL-cholesterol, VLDL-cholesterol and triglycerides. HDL-cholesterol was also determined . The animals then sacrificed and specimens were taken from the liver and kidney tissues and tissue homogenates were done for determination of antioxidant parameters as Malondialdehyde (MDA), Reduced Glutathione (GSH) and catalase(CAT) levels estimation. Results: chronic oral administration of raw garlic homogenate in STZ-induced diabetic rats produced significant reduction in serum levels of glucose(P<0.01), AST (P<0.05 , ALT(P<0.05), ALP(P<0.05),bilirubin (P<0.01), urea (P<0.01) and creatinine (P<0.05) furthermore,there is a significant decrease in total serum cholesterol (P<0.05), LDL-cholesterol(P<0.01) , VLDL-cholesterol(P<0.05) , and triglycerides (P<0.05) and significant increase in HDL-cholesterol (P<0.01) as compared with control group. On the other hand hepatic (P<0.01) and renal(P<0.05) MDA was significantly reduced. Also, there is significant increase in both hepatic (P<0.01) and renal (P<0.05) GSH levels and catalase activity (P<0.001) as compared with STZ-induced diabetic rats. conclusion : chronic oral administration of raw garlic homogenate prevent oxidative stress and associated biochemical changes in STZ-induced diabetic rats.