Background In congenital aortic stenosis (CAS), commissurotomy is an option in patients not suitable to receive a valve prosthesis. However, there is often a need for future additional interventions on the aortic valve. The fate of the aortic valve is, however, essentially unknown. This study reports the need for reinterventions after surgical commissurotomy, based on a national register. Materials and methods The national register on congenital heart diseases (CHDs) was searched for patients with CAS, simple or associated with other CHD and an index commissurotomy with later data from follow-up. Results 300 patients with CAS and an index commissurotomy (mean age at the operation 7.4 +/- 7.8 years, 72.4% males) were identified. After an observation time of 27.4 +/- 10.0 years, 54.7% of the patients had a reintervention that occurred 14.2 +/- 10.1 years after the index operation. The cumulative incidence of reintervention was approximately 25% 10 years after and 60% 30 years after the index intervention. The prevalence of left ventricular hypertrophy (LVH) was higher among those that needed reintervention (41.3 vs 26.8%, p=0.023). Furthermore, eight patients died with a cumulative incidence of 7% 30 years after the index intervention, where most were (7/8) without reintervention (p=0.025). There were no additional important differences between patients with and without reintervention. The prevalence of left ventricular dysfunction and New York Heart Association class >1 was low. Conclusion Most (54.7%) patients with a commissurotomy, more than half of them within 30 years and eventually all will need a reintervention. This is important information to patients, especially for women in childbearing age. The higher prevalence of LVH in the group with reintervention needs attention during follow-up. Furthermore, those without reintervention, for unknown reasons, had a higher mortality. Our data strengthen the arguments for close outpatient follow-up among patients with a previous commissurotomy.