We aimed to evaluate the correlation between aortic regurgitation severity and brain natriuretic (BNP) levels as a marker for left ventricular dysfunction. Sixty consecutive male patients (mean age 22 +/- 3 years) with isolated chronic aortic regurgitation were enrolled in the study together with a control group of 30 age-matched healthy volunteers (group A). Patients were classified with regard to aortic regurgitation vena contracta width as follows: group B, < 3 mm, mild (n = 16); group C, > or = 3 and < 6 mm, moderate (n = 26); group D, > or = 6 mm, severe (n = 18). BNP measurements were performed with a fluorescence immunoassay kit. BNP levels were increased in patients with aortic regurgitation, and severity of regurgitation had a significant influence on BNP levels. This effect can be explained by the volume loading effect of aortic regurgitation.