This study aimed to evaluate the changes in left and right ventricular functions of children with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) and to determine the efficacy of surgical treatment for OSAHS in children. The subjects included 20 normal controls and 55 children of OSAHS with adenoid and/or tonsil hypertrophy diagnosed by polysomnography (PSG). We divided the children with OSAHS into the mild group, moderate group and severe group of OSAHS according to the condition of apnoea-hypopnoea index (AHI) and the lowest ofoxygen saturation (LSaO(2)). In mitral annulus,the Va values were increased in moderate and severe OSAHS (P>0.05), and the Ve/Va values were decreased in the severe group (P>0.05), while the Vs values were not changed (P>0.05). In tricuspid annulus, the Vs values were decreased in moderate and severe OSAHS (P<0.05), while the Ve, Va and Ve/Va values were not changed (P>0.05). Six months after adenoidectomy and/or tonsillectomy, mitral Va values were decreased and tricuspid Vs values were increased significantly (P<0.05), and AHI was decreased and LSaO(2) was significantly increased (P<0.05). Compared with the control group, no difference was found in the above parameters (P>0.05). The left ventricular diastolic function and the right ventricular systolic function of children with moderate to severe OSAHS are decreased to varying degrees at an early stage. Mitral annular and tricuspid annular velocity detected by quantitative tissue velocity imaging (QTVI) could sensitively reflect the early changes of left and right ventricular function. Adenoidectomy and/or tonsillectomy wereeffective methods to treat childhood OSAHS, which could reverse myocardial dysfunction.