Eleven cases of cor pulmonale secondary to tonsil and adenoid hypertrophy and upper airway obstruction were reviewed. These patients presented with a spectrum disease ranging from mild, with only abnormal ECG or chest X-ray findings, to severe with hypercarbia, hypoxia, and right heart failure. One patient with severe disease suffered a postoperative respiratory arrest. We have successfully managed 4 patients with severe cor pulmonale with postoperative intubation and assisted ventilation. Hypoxia is the driving stimulus for respiration in patients with upper airway obstruction and hypercarbia. Relief of respiratory obstruction by tonsillectomy and adenoidectomy with postoperative oxygen administration may remove the hypoxic drive, resulting in respiratory arrest. Patients undergoing tonsillectomy and adenoidectomy for upper airway obstruction disease should be screened for cor pulmonale. Affected patients should be managed after surgery in an intensive care unit (ICU) environment with careful monitoring of the respiratory status. Patients with severe cor pulmonale can be successfully managed with planned postoperative intubation and mechanical ventilation to prevent respiratory arrest.