Background: Oxidative DNA damage due to reactive oxygen species(ROS) has been implicated in cardiovascular diseases. Deoxyguanosine is one of the constituents of DNA and when it is oxidized, it is altered into 8-OHdG. The serum concentration of the DNA repair product 8-OHdG has been proposed as a noninvasive biomarker of oxidative DNA damage in human in vivo. Carvedilol has shown to have antioxidant actions in patients by reduction of anti-oxidized LDL antibodies and to reduce ROS in normal human subjects. However, there has been no data that carvedilol reduce DNA damage in human hypertension. Methods: Seventeen newly diagnosed hypertension patients (mean age =51짹11, male/female=11/6) who have not taken antihypertensive medication previously volunteered for the study. Fasting blood sample were collected at baseline in tubes with EDTA as an anticoagulant. The subjects were given 12.5 or 25 mg of carvedilol PO once a day for 2 months. Two months later, another blood sample was collected as above. Age and sex matched control subjects (n=22, mean age =45짹12, male/female=14/8), not given any drugs, also had 2 samples taken 2 months apart. None of the subjects were on any medications, including NSAIDs, Vitamin E, or other antioxidants. Serum 8-OHdG was measured with ELISA method. High sensitivity C-reactive protein (hs-CRP) was also checked two times. There were no statistical differences in smoking, diabetes, and total cholesterol level between hypertension and control group. Results: In the hypertension group, DNA damage biomarker 8-OHdG at baseline was 9.07짹4.23 ng/ml (mean짹SD). After carvedilol administration, it fell to 5.74짹3.89 ng/ml (p=0.002). In the control group, the 8-OHdG concentrations were 3.41짹2.03, 3.01짹2.65 ng/ml at baseline and 2 months later, respectively (p=NS). The baseline 8-OHdG was higher in the group of hypertension than in control(p=0.001). hs-CRP had no significant difference before and after carvedilol treatment in the hypertension group( 0.21짹0.51, 0.19짹0.37 mg/dl). Conclusion: DNA damage due to ROS occurs more in hypertension patients than in normal blood pressure people. Carvedilol may significantly reduce DNA damage in hypertension patients.