The serial changes in aortic regurgitation (AR) after balloon aortic valvuloplasty have not been quantitatively evaluated. This study assessed the degree of AR by quantitative and qualitative techniques before and immediately after aortic valvuloplasty. Digital subtraction aortography was performed before and after valvuloplasty in 50 patients. The ratio of left ventricular to aortic contrast density during aortography was analyzed by videodensitometric techniques. A time-density curve was obtained by placing a 30 X 30 pixel region of interest over the aortogram and the left ventricular cavity. The ratio of left ventricular to aortic density at peak aortic density defined the videodensitometric ratio. Independent visual interpretation was also assessed and compared to videodensitometric methods. Quantitatively, no significant change in AR could be demonstrated in the mean videodensitometric ratio before or after balloon aortic valvuloplasty (0.33 +/- 0.21 vs 0.37 +/- 0.25, p = 0.07). Ten (20%) of the patients had a greater than or equal to 0.10 increase, and 4 (8%) patients a greater than or equal to 0.10 decrease in the AR ratio. Thus, serial quantitative and qualitative determinations of AR after balloon aortic valvuloplasty confirm that significant increases or decreases in AR severity are unusual after the procedure.