Obstructive sleep apnea secondary to adenotonsillar hypertrophy is one of the rare causes of pulmonary hypertension in children. We hereby report a case of OSA secondary to adenotonsillar hypertrophy, managed at AIIMS Rishikesh with remission of pulmonary hypertension following adenotonsillectomy. A 4year old male child presented with cough, difficulty in breathing, noisy breathing, day time somnolence from last 1 year. Grade 4 adenoid hypertrophy with grade 3 tonsillar hypertrophy was seen on ENT evaluation. A 2D–echocardiography showed severe pulmonary artery hypertension with moderate Tricuspid regurgitation with good biventricular function. His final diagnosis was severe pulmonary artery hypertension with right–sided heart failure due to OSA secondary to adenotonsillar hypertrophy. He had complete remission of cardiopulmonary symptoms with resolution of pulmonary hypertension after adenotonsillectomy. Children with OSA with cardiopulmonary involvement could benefit from routine screening for pulmonary hypertension. Adenotonsillectomy should be considered for remission of OSA due to adenotonsillar hypertrophy with cardiopulmonary symptoms.