Background: Diabetes is a metabolic disease that is associated with hyperglycemia and infertility. Previous studies indicate that aloe vera may positively affect the blood glucose and fertility. Objective: the present study was carried out to evaluate effect of aloe vera on serum oxidant/antioxidant activity and reproductive hormones following experimental diabetes. Methods: sixty adults male wistar rats were divided to 5 groups. control group(A) was kept without treatment. Group(E) only received aloe vera gel(400 mg/kg-orally). Experimental diabete mellitus was induced in 3 groups of rats by streptozotocin( 65 mg/kg-Ip). One diabetic group was kept without treatment(B). Another diabetic group received aloe vera gel(400 mg/kg-orally)(C) and another received insulin(10 units)(D). Aloe vera gel and insulin was administration for 30 days then, the rats were anesthetized and blood collected. The amount of malondialdehid(MDA), anti oxidant activity(AOA), glutathion peroxidase activity(GPX), thiol protein(TSH), testosterone, LH and FSH was determined in serum. Results: level of testosterone was significantly decreased while amount of MDA, TSH, GPX and AOA was significantly increased in non-treated diabetic rats. Aloe vera increased antioxidant defense. Conclusions: Aloe vera improves antioxidant activity and reduces diabetic complications. Key words: Diabetes, Aloe vera, Anti oxidant, pituitary – sexual hormones, rat.