BACKGROUND: Thoracic mobilisation improves thoracic hyperkyphosis and respiratory function. Diaphragmatic excursion is associated with respiratory function; however, limited studies have assessed the effect of thoracic mobilisation on diaphragmatic excursion. OBJECTIVE: This study aimed to investigate the effects of thoracic mobilisation on diaphragmatic excursion and respiratory function in individuals with thoracic hyperkyphosis. METHODS: Participants were recruited through Internet advertising and participated voluntarily. Nineteen healthy participants (age: 33.37 ± 6.56 years; height: 170.32 ± 7.92 cm; weight: 69.77 ± 14.70 kg) with thoracic hyperkyphosis underwent thoracic mobilisation for 8 weeks. Diaphragmatic excursion, thoracic kyphosis, and respiratory function were measured. Thoracic mobilisation was provided using a mechanical massage device. RESULTS: Thoracic mobilisation for 8 weeks significantly improved diaphragmatic excursion during deep breathing (p= 0.015), forced vital capacity (p< 0.01), and thoracic hyperkyphosis (p< 0.01). CONCLUSIONS: Thoracic mobilisation can be recommended in respiratory rehabilitation programs to increase diaphragmatic excursion and respiratory function for the management and prevention of respiratory dysfunction in individuals with thoracic hyperkyphosis.