As increasing evidence suggest that oxidative stress plays an important role in the developing angiopathy in diabetes, we studied the effects of taurine, a free radical scavenger, on diabetes induced angiopathy in the rat aorta. Six-week-old male Wistar rats were randomly divided into three groups; control group (Cont), diabetes group (DM) and diabetes group treated with taurine for four weeks, 500 mg/kg/day, intraperitoneally (i.p.) (DM+T). Diabetes was induced by streptozotocin (50 mg/kg i.p.). Four weeks after the induction of diabetes, serum glucose and malondialdehyde concentrations were measured. Additionally, organ bath studies and real-time PCR on muscarinic M(3) receptor and eNOS were performed. Although taurine treatment failed to decrease serum glucose levels, the increased serum malondialdehyde levels in diabetic rats were significantly decreased after taurine treatment. Norepinephrine-induced hyper-contractility as well as acetylcholine-induced, endothelium-dependent hypo-relaxation in diabetes were significantly prevented after taurine treatment. The differences in the expressions of muscarinic M(3) receptor mRNAs were statistically non-significant between groups. Moreover, diabetes-induced up-regulation of eNOS mRNAs was slightly prevented after taurine treatment. These data suggest that taurine acts beneficially against the diabetes-induced vascular dysfunction. Its potential action as a radical scavenger ameliorates the vascular disorders in diabetes.