Early and late results after surgery for isolated congenital valvar aortic stenosis were evaluated in a total of 86 children under 16 years of age (mean 7.4 years). Primary procedure was always conservative. There were 7/86 (8.1%) early deaths. All infants who died after the operation were younger than 4 months of age. Among the clinical variables tested by the univariate analysis only age and duration of cardiopulmonary bypass were significant prognostic factors for early death. There were 6/67 (7.7%) valve-related late deaths. Multivariate analysis could not identify any risk factors for early and late mortality. Actuarial survival was 97% (95% CL 93-101%) after 5 years, 94% (88-100%) after 10 years, 90% (82-98%) after 15 years, and 87% (77-97%) after 20 years. A total of 22/79 (28%) early survivors had a first reoperation and 5 had a second reoperation. Long follow-up interval was the only significant factor for reoperation. Actuarial reoperation-free interval was 91% (85-98%) after 5 years, 70% (58-81%) after 10 years, and 50% (34-64%) after 15 years. Significant factors for poor valve function were long duration of follow-up, endocarditis, and young age at operation. The probability of normal valve function was 91% (84-98%) after 5 years, 67% (55-79%) after 10 years, and 54% (40-68%) after 15 years.