BACKGROUND AND OBJECTIVES: Essential hypertension has been accepted as being associated with a loss of the balance between pro- and anti-oxidations. Essential trace elements, such as Se, Mn, Cu and Zn, participate in various enzyme reactions necessary for the antioxidant defense system of cells. The object of the present study was to evaluate the serum levels of anti-oxidant minerals, which may be related to the pathophysiology of essential hypertension. SUBJECTS AND METHODS: The subjects were composed of 50 normotensive controls; 25 men and 25 women (14 premenopausal, 11 postmenopausal), and 50 hypertensive patients; 16 men and 32 women (19 premenopausal, 13 postmenopausal). ICP-MS was employed to measure the mineral concentrations. RESULTS: Compared with controls, the serum Se and Zn concentrations in the essential hypertensive patients were elevated (Se 12.78+/-0.47 vs. 17.85+/-0.58 microliter/dL, p=0.0008; Zn 110.87+/-5.36 vs. 134.36+/-5.95 microliter/dL, p=0.0040), whereas those of Mn and Cu were decreased (Mn 0.49+/-0.02 vs. 0.28+/-0.03 microliter/dL, p=0.0121; Cu 127.84+/-5.07 vs. 93.88+/-2.90 microliter/dL, p<0.0001). The mean Cu/Zn ratio of the patients was higher than that of the controls (1.14+/-0.03 vs. 0.67+/-0.02, p=0.0057). In the hypertensive patients, there was a negative correlation between the Zn and Cu concentrations (correlation coefficient -0.36458, p=0.0395). CONCLUSION: The analyzed mineral concentrations were significantly different between the essential hypertensive patients and the controls. It remains to be determined whether the alterations in the serum concentrations of antioxidant minerals are responsible for the pathogenesis of essential hypertension or just a simple consequence of hypertension.