Increased activity of the renin angiotensin system with enhanced levels of angiotensin II leads to oxidative stress with endothelial dysfunction, hypertension, and atherosclerosis. Epidemiologic studies revealed a higher cancer mortality and an increased kidney cancer incidence in hypertensive patients. Because elevated angiotensin II levels might contribute to carcinogenesis, we tested whether angiotensin II induces DNA damage in the kidney. In isolated perfused mouse kidneys, as little as 1 nmol/L angiotensin II caused a significant increase in DNA strand breaks, measured with the comet assay. This damage was independent of the hemodynamic effect of angiotensin II and mediated by the angiotensin II type 1 receptor. Angiotensin II also caused double-strand breaks in the cells of the isolated perfused kidney, detected with an antibody against the double-strand break marker gamma-H2AX. Studies in cell culture allowed further characterization of the DNA damage induced by angiotensin II. Single- and double-strand breaks, abasic sites, and 7,8-dihydro-8-oxo-guanine, all types of oxidative DNA lesions, were detected in angiotensin II-treated renal cells. The majority of detected strand breaks was repaired within 1 hour, but double-strand breaks increased and persisted for at least 24 hours.