To compare characteristics of aortic regurgitation (AR), the results of 213 procedures (110 balloon aortic valvotomies [BAV] and 103 surgical aortic valvotomies [SAV]) for treatment of congenital aortic valve stenosis were reviewed. These procedures were performed in 187 patients from June 1981 to September 1993. Echocardiograms recorded immediately before, within 6 months afterward, and at latest follow-up were compared. Color Doppler was used to assess the degree of AR and was quantified as the ratio of the regurgitant jet width to valve annulus, the jet width ratio. Whereas BAV patients were older (median age 5.7 years vs 3 months; p = 0.0001), there was no significant difference in median follow-up interval (3.1 years [range 0.5 to 7.2] for BAV vs 3.6 years [range 0.6 to 10.4] for SAV; p = 0.44). The mean balloon-to-annulus ratio for BAV was 0.99 +/- 0.09. An open valvotomy was performed in 83% of surgical cases. Acute systolic gradient reduction and subsequent increase at late follow-up was similar for both groups. Acutely, the mean jet width ratio increased similarly (p = 0.84) for BAV (+9 +/- 15%; p = 0.0001) and SAV (+9 +/- 12%; p = 0.0003) and was not related to age at procedure. At late follow-up, mean jet width ratio further increased significantly in both groups, although there was no difference (p = 0.17) in amount of progression (BAV +10 +/- 12%; p = 0.0001, SAV +15 +/- 13%; p = 0.0002). Thus, BAV and SAV produce AR of similar severity with similar rates of progression.