["To assess the long term results of a transnasal endoscopic, power-assisted marsupilization of Thornwaldt's cyst (TC).", 'Patients who were operated and followed up at our institution for the management of symptomatic TC in the period from February 2002 till May 2012 were included in the study. All the patients were operated through a transnasal endoscopic power-assisted marsupilization of the cyst.', 'Eleven patients with a diagnosis of TC (by nasaoendoscopy, CT and MRI) were included in this study. They included six males and five females with age ranging from 15 to 55 years. Transnasal endoscopic, power-assisted marsupilization was performed for all cases with no intra- or postoperative complications. Throughout 5 years follow up, no recurrence of the cyst or its related symptoms were reported.'] Do 5 years follow up after transnasal endoscopic surgery of Thornwaldt 's cyst with powered instrumentation?