It is well known that blood pressure (BP) management reduces the incidence of cerebrovascular and cardiovascular events. However, it is unclear how many of these events occur in hypertensive patients who receive pharmacological treatment. The aim of this survey was to evaluate the occurrence rate of both types of events in patients receiving valsartan-based treatment. Of 30 366 patients treated with valsartan, 28 356 patients were observed for 2.93 years. Antihypertensive drugs other than valsartan were used in 56.8% of patients. After the administration of valsartan, the systolic and diastolic BP significantly decreased from 161.1±19.1/90.4±13.1 to 139.9±18.1/79.6±11.9 mm Hg. Cerebrovascular events were observed in 550 patients (1.94%, 9.29/1000 patient-years), and cardiac events were observed in 576 patients (2.03%, 9.73/1000 patient-years). A comparative analysis of the hazard ratios for cerebrovascular and cardiac events according to the BP level at the endpoint showed a BP-dependent reduction of risk for cerebrovascular events, and the change in risk exhibited a J-curve phenomenon in the relationship between cardiac events and systolic BP. The J-curve phenomenon was not observed in patients aged <75 years, but it was observed for the systolic BP in patients aged 75 years. Adverse drug reactions were observed in 1925 of 28 420 patients (6.77%). This post-marketing surveillance data for valsartan showed the outcomes for treated hypertensive patients in a large population in Japan who were followed for up to 3 years. These data will add important knowledge regarding the treatment of hypertension in Japan.