Angiotensin-converting enzyme (ACE) and paraoxonase1 (PON1) genes are considered as candidates for diabetic nephropathy since oxidative stress may play an important role in the development of diabetic complications.  The aim of our study was to examine whether there is an association between genetic variants of PON1 and ACE genes and markers of oxidative stress in both diabetic patients with and without nephropathy. The activities of ACE and GSH-Reductase (GSH-Rd) were significantly higher but PON1 activity was found lower in diabetic patients without nephropathy as compared with controls. The decrease in PON1 activity was more evident in diabetes with nephropathy as compared with diabetes without nephropathy. Diabetic patients with nephropathy and those without complication had higher levels of malondialdehyde (MDA) than controls. Both diabetic patients with and without nephropathy carrying RR and LL genotypes had significantly higher PON1 activity than diabetic patients with and without nephropathy carrying QQ and MM genotypes. ACE activity was found increased significantly in all population carrying DD genotype. Our findings have support the hypothesis that oxidative stress may play an important role in diabetes mellitus (DM). Additionally, the impaired antioxidant activity of PON1 independent of PON1 55/192 polymorphisms may be involved in the complications of diabetes.