Background: There are conflicting reports about zinc, a trace element, in the pathogenesis of hypertension and other cardiovascular diseases. The aim of this study was to evaluate the role of zinc in high blood pressure.Methods: We conducted this study on 80 patients with primary (idiopathic) hypertension and 80 normotensive people with similar age who attended to Tehran Heart Center between 2007 and 2008. We examined the effect of zinc concentration on blood pressure in both sexes in four age groups (41-50, 51-60, 61-70 and 71-80 years old). We measured plasma zinc concentration by atomic absorption.Results: The mean plasma zinc concentrations were 0.456±0.04 μg/ml and 0.551±0.055 μg/ml in patients with hypertension and in normotensive people, respectively, (P≤0.05). Nevertheless, the mean plasma zinc concentrations were 0.494 μg/ml and 0.486 μg/ml in men with and without hypertension, respectively. The mean plasma zinc concentrations of women with and without hypertension, respectively were 0.415 μg/ml and 0.596 μg/ml, showing a significant difference between two groups (P≤0.001). Moreover, there was a significant difference in plasma zinc concentration between hypertensive and normotensive people in 51 to 60 years age group (P≤0.05), but difference were not significant between other age groups.Conclusion: The results of this study revealed the relationship between the decrease in plasma zinc concentration and increase in blood pressure in women and in the men aged 51 to 60 years.