Background and Aims: The long-term respiratory sequelae of COVID-19 infection in children remain poorly understood and may differ across countries. This study aims to investigate the respiratory sequelae, including residual respiratory symptoms and pulmonary function in Thai children. The secondary aim is to identify factors associated with the respiratory sequelae. Materials and Methods: This is an observational study involving 56 healthy children, aged between 7-18 years, who were diagnosed with COVID-19 infection from July 2021 to February 2023. Clinical data relating to COVID-19 infection and persistent symptoms after the infection were assessed after the infection up to six months. Spirometry was performed to assess pulmonary function. Results: Post COVID-19 symptoms were identified in 14 patients (25%), with fatigue, cough, and dyspnea being common symptoms (28-35%). A significant correlation was found between post COVID-19 symptoms and pneumonia (OR = 6.00, 95%CI [1.54,23.33], p=0.01). Abnormal pulmonary function was identified in 10 patients (17.8%) with obstructive impairment being the most common. However, there were no significant association between clinical factors and pulmonary function impairment. Conclusion: Prolonged respiratory symptoms and abnormal pulmonary function following COVID-19 infection are not uncommon in children. The post COVID-19 symptoms are possibly associated with COVID-19 pneumonia.