Thoracic kyphosis represents a widely spread spinal deviation that affects an increasing number of children and adolescents. It effects not only the development of children but can also have consequences on the ventilatory parameters and on the aerobic functional capacity. The objectives of our study were to assess the respiratory function and functional capacity in children and adolescents with thoracic kyphosis who followed a physical therapy program and to compare these parameters to healthy controls. Another objective was to evaluate the adherence of this category of patients to a supervised exercise program. 20 children and adolescents diagnosed with thoracic kyphosis and 20 gender and age-matched healthy controls were included in the study. Our patients performed a twelve-week supervised exercise program. They were assessed at the beginning and at the end of rehabilitation by spirometry (forced vital capacity-FVC, forced expiratory volume in 1 second-FEV1, peak expiratory flow-PEF and FEV1/FVC ratio) and functional capacity testing (6-minute walk test: 6MWT). A final assessment was conducted with the parents of the children and the adolescents with thoracic kyphosis where they completed an adherence questionnaire. In patients with thoracic kyphosis, their FVC, FEV1, PEF and 6-MWT scores improved significantly after the twelve-week program (p˂0.0001). After rehabilitation there were no differences between the study patients and controls, except for the functional capacity which had lower values in children and adolescents with thoracic kyphosis. Adherence to an exercise-based program could improve the outcomes of the rehabilitation. Besides the respiratory function and functional capacity, assessing adherence to therapy and improving it should be considered when treating pediatric patients suffering from thoracic kyphosis.