Background: One of the main goals of corrective surgery of congenital heart defects in children is the improvement of quality of life, which in young children is predominantly determined by exercise capacity. It is not known whether this goal can be achieved in school-aged children who have undergone cardiac surgery in infancy. Objectives: To determine if primary schoolaged children who underwent surgery to correct congenital heart defects in infancy are physically as fit as their peers. Methods: We examined 84 children with congenital heart defects, aged 4 to 11 years, after surgical repair. Fifty-two children had simple defects (ie, atrial or ventricular septal defect, coarctation of the aorta). Thirty two children had complex defects (ie, tetralogy of Fallot, pulmonary atresia with ventricular septal defect). All patients underwent exercise testing performed on a specially modified bicycle ergometer. Ninety-eight sex- and age-matched healthy children served as the control group. Results: There was no gender difference, either in healthy children or in the group with congenital heart defects, regarding exercise testing and that the healthy children reached a mean ± SD normalized maximal performance of 2.8 ± 0.3 W/kg. The same range was found for the children who had undergone surgery to correct simple heart defects. The children operated on to correct complex heart defects showed significantly impaired mean normalized maximal performance, although this tended to be lower in the group that had pulmonary atresia with a ventricular septal defect than in the group with tetralogy of Fallot (mean normalized maximal performance, 1.9 W/kg vs 2.3 W/kg). Conclusions: The goal of normal exercise capacity in childhood after heart surgery is achieved in those with simple heart defects only. In children with complex heart defects impaired exercise performance persists, depending on the severity of the heart defect and probably on chronotropic incompetence. Background: One of the main goals of corrective surgery of congenital heart defects in children is the improvement of quality of life, which in young children is predominantly determined by exercise capacity. It is not known whether this goal can be achieved in school-aged children Who have undergone cardiac surgery in infancy. Objectives: To determine if primary schoolaged children who underwent surgery to correct congenital heart defects in infancy are physically as fit as their peers. Methods: We examined 84 children with congenital heart defects, aged 4 to 11 years , after surgical repair. Fifty-two children had simple defects (ie, atrial or ventricular septal defect, coarctation of the aorta). Thirty two children had complex defects (ie, tetralogy of Fallot, pulmonary atresia with ventricular septal defect). All patients underwent exercise testing performed on a specially modified bicycle ergometer. Ninety-eight sex- and age-matched healthy children served as the control group. Res ults: There was no gender difference, either in healthy children or in the group with congenital heart defects, regarding exercise testing and that the healthy children reached a mean ± SD normalized maximal performance of 2.8 ± 0.3 W / kg. The same range was found for the children who had undergone surgery to correct simple heart defects. The children operated on to correct complex heart defects showed significantly impaired mean normalized maximal performance, although this tended to be lower in the group that had pulmonary atresia with a ventricular septal defect than in the group with tetralogy of Fallot (mean normalized maximal performance, 1.9 W / kg vs 2.3 W / kg). Conclusions: The goal of normal exercise capacity in childhood after heart surgery is achieved in those with simple heart defects only. heart defects impaired exercise performance persists, depending on the severity of the heart defect and probably on chronotropic incompetence.