The present study aimed to investigate the right ventricular function in children with obstructive adenotonsillar hypertrophy. For this purpose, right ventricular diastolic functions were evaluated via echocardiography before adenotonsillectomy and after a minimum of 6 months following surgery. Children with adenotonsillar hypertrophy who were admitted to our clinic with the complaints of snoring, mouth breathing, and/or witnessed apnea were included. Pre-operatively, a complete blood cell count, routine biochemical blood tests, chest radiography, electrocardiography, and tissue Doppler echocardiography were performed. Electrocardiography and tissue Doppler echocardiography were repeated on the follow-up visits of the patients a er a minimum of 6 months following adenotonsillectomy. Evaluation of the patients in the post-operative 6th month revealed no snoring or apnea in any of the patients. Although significant changes were detected in certain echocardiographic parameters a er the surgery, right ventricular morphological abnormalities were not detected. Also, echocardiographic measurements of le ventricular dimensions were within the normal limits. Nevertheless, the ratio of peak early to late tissue motion velocity of the tricuspid valve as determined by tissue Doppler imaging was higher in the post-operative period than in the pre-operative period. This might be attributed to the relative improvement in diastolic functions.