Although adenotonsillectomy is usually considered a minor operation, numerous uncommon but severe complications have been described. Even tonsillectomy alone can cause velopharyngeal insufficiency (VPI). We describe two cases in which severe VPI was noted after palatine tonsillectomy was performed because of recurrent peritonsillar abscesses. The patients underwent clinical examination, nasalance measurements, videonasopharyngoscopy and videofluoroscopy. Findings in both patients were consistent with lesions of branches of the vagus and glossopharyngeal nerves through lingual rami, while one of the patients probably also had a lesion of the hypoglossal nerve. Endoscopic and videofluoroscopic examinations demonstrated essential differences in the patients' preoperative state of velopharyngeal anatomy. Findings demonstrate the value of careful postoperative endoscopic and videofluoroscopic examination in cases with VPI after tonsillectomy to identify factors affecting subsequent VPI and to design possible treatment.