The purpose of this study was to validate and re-evaluate our previously reported scoring systems for predicting optimal management in neonates with aortic stenosis (AS). In 1991, we reported a multivariate discriminant equation and an ordinal scoring system for predicting which neonates with AS are suitable for biventricular repair and which are better served by single ventricle management. Retrospective analysis was performed to: 1) validate our scoring systems in 89 additional neonates with AS and normal mitral valve area, 2) assess the effects of 5% measurement variation on predictive scores, 3) evaluate our cohort with the Congenital Heart Surgeons' Society scoring system, and 4) repeat the discriminant analysis on the basis of all 126 patients. The original scores each predicted outcome accurately in 68 patients (77%). Minor (5%) measurement variation changed the outcome predicted by the discriminant equation in 8 patients (9%) and by the threshold system in 13 patients (15%). The most accurate model for predicting survival with a biventricular circulation among the full cohort is: 10.98 (body surface area) + 0.56 (aortic annulus z-score) + 5.89 (left ventricular to heart long-axis ratio) - 0.79 (grade 2 or 3 endocardial fibroelastosis) - 6.78. With a cutoff of -0.65, outcome was predicted accurately in 90% of patients. Both of our original scoring systems are less accurate at predicting outcome than in our original analysis. Revised discriminant analysis yielded a model similar to our original equation that was 90% accurate at predicting survival with a biventricular circulation among neonates with AS and a mitral valve area z-score >-2.