Obstructive sleep apnoea (OSA) in children is a prevalent sleep disorder, and is characterised by repetitive complete or partial upper airway obstruction during sleep. It is an important disease as it is associated with a large spectrum of end-organ morbidities. Adenotonsillar hypertrophy is the commonest cause of OSA in children, however, the cause of the lymphoid tissue hypertrophy in some individuals but not the others remains unknown. To address the cellular heterogeneity and immune cell involvement in adenotonsillar hypertrophy, here, we propose to employ single-cell sequencing analysis to identify the cell-specific expression patterns associated with the disease, which will enhance our understanding of the pathogenesis of tonsillar hypertrophy in children with OSA and may provide directions for development of novel therapy.