We examined the effects of aging and hypertensive left ventricular hypertrophy on the plasma level of brain natriuretic peptide (BNP), and assessed BNP as a risk marker for incident hypertensive cardiovascular events. One hundred and eighty-five hypertensive patients were echocardiographically divided into a hypertensive group with normal left ventricular mass (n =96; age range, 37-86 years; left ventricular mass, 97±14 g/m²) and a hypertensive group with left ventricular hypertrophy (n =89; 37-90 years; 140±20 g/m²). Forty-four normotensive subjects served as the normotensive group (32-84 years; 91±15 g/m²). We examined the association of age with BNP in the three groups and also evaluated BNP as a risk marker for incident cardiovascular events by following up all patients for 40 months. All three groups demonstrated a significant positive relationship between age and BNP. The slope of the relation between age and BNP was steepest in the hypertensive group with left ventricular hypertrophy (p <0.0001 vs. the other two groups). Multiple regression analysis revealed that age, pulse pressure and left ventricular mass index were significantly associated with the increase in BNP. Multivariate Cox proportional hazards regression analysis, which was used to assess the potential association of age, pulse pressure, left ventricular mass index and BNP with the cardiovascular events during follow-up, revealed the highest correlation between BNP and incident cardiovascular events (risk ratio=1.011; p =0.0011). BNP, which is synergistically increased with aging and left ventricular hypertrophy, may be an important risk marker for hypertensive cardiovascular events. (Hypertens Res 2002; 25: 669-676)