Background: Surgical treatment methods are still controversial in children with congenital or acquired aortic valve dysfunction. Aim: To evaluate treatment results in children after mechanical or biological valve implantation. Methods: We analysed a group of 55 children after mechanical valve implantation (group A) and a group of 8 children after Freestyle biological valve implantation (group B). We evaluated in both groups: patient’s age, type of valve dysfunctions, severity of heart failure symptoms, and quality of life. The parameters of physiological left ventricular (LV) remodelling were examined on the basis of echocardiographical signs of LV contractibility (%SF) and anatomical changes: LV diastolic diameter (LVDd), LV posterior wall thickness (LVPW), thickness of intra-ventricle septum (IVS) and pressure gradient between LV and aorta (LV-Ao). Results: There were no hospital deaths in either group. There were two late deaths in children from group A. Thromboembolic (2), nonspecific bleeding complications (2), and infections (2) occurred in group A. There were two re-operations in children after mechanical valve implantation. The early postoperative period was good in groups A and B. Furthermore, late postoperative period was good in group B. Physiological LV remodelling occurred in children in groups A and B. Quality of life was good in both groups. Conclusions: Good clinical results, simplicity, repeatability and safety of surgical technique mean that mechanical valve implantation in the aortic position is still an attractive option for treatment in children and adults. However, absence of bleeding, thromboembolic and infection complications and improvement of durability mean that the Freestyle biological new generation valve could be a good option for future in children and adolescents who need aortic valve replacement.