In this study we estimated nitric oxide (NO) in hypertensive patients with and without complication. No measured in three groups of patients, G1 complicated hypertensive group, G2 uncontrolled hypertensive group, G3 controlled hypertensive group and compared to group of normal person (G4). We found that (NO) level decreased in all hypertensive group, compared to normal control group, the decrease was more evident in uncontrolled group. So nitric oxide could be considered as independent risk factor for complications of hypertension.