Objective: Adenotonsillar hypertrophy causing upper airway obstruction may lead to the pulmonary hypertension and cor pulmonale. This study aimed to clarify the diagnostic methods of this complication, besides polysomnography, to find another objective criterion for surgical intervention and to demonstrate the curative effect of adenotonsillectomy on this complication using this objective criterion. Methods: We studied the outcomes of 17 children with pulmonary hypertension secondary to the adenotonsillar hypertrophy. Pulmonary arterial pressure measurement was performed noninvasively by Doppler echocardiography. Results: Mean preoperative pulmonary arterial pressure was 29.12 +/- 4.11 mmHg and decreased dramatically after relief of upper airway obstruction by adenoidectomy and/or tonsillectomy to the normal level of 12.06 +/- 3.09 mmHg. These results were analyzed by equal variances t-test and found very significant (P < 0.01). Regarding the symptoms of upper respiratory obstruction, symptom scores of these children decreased very significantly and were analyzed by equal variances t-test (P < 0.01) in the postoperative period. For all the symptoms individually (snoring, mouth-breathing during sleep and daytime, hyponasal voice, restless sleeping, daytime somnolence, enuresis nocturnal), comparing percentages of preoperative and postoperative symptoms by unequal variances t-test, we obtained very significant decrease (P < 0.01). Conclusions: This study illustrates that Doppler echocardiography is a safe, practical and noninvasive - method in diagnosing cardiovasculary disturbances - one of the complications of adenotonsillar hypertrophy and especially for measuring the pulmonary arterial pressure. All the symptoms and disorders due to the adenotonsillar hypertrophy may be reversible by performing early adeno- and/or tonsillectomy. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.