Since 1984 at the Department of Otorhinolaryngology, Head and Neck Surgery, University of Kiel, 34 patients with hypopharyngeal diverticular have been operated microendoscopically using the CO2 laser. Results and complications of this technique were compared to a group of patients in whom standard (non-laser) diverticulotomy was carried out from 1976 to 1993. Ninety per cent of the patients treated endoscopically with laser surgery have not had complaints and the rate of postoperative complications has been low. Three patients developed pharyngeal stenoses while one case incurred a mediastinitis. Intraoperative bleeding was not observed. In comparison to the microendoscopic procedure serious complications were more frequently observed in patients treated with the standard diverticulotomy. In eight of these cases paralysis of the recurrent laryngeal nerve occurred. A mediastinotomy was performed in another three patients because of mediastinitis. In two cases stenosis occurred after surgery and one patient developed a fistula. Endoscopic diverticulotomy utilizing a CO2 laser was found to be an excellent treatment for Zenker's diverticulum because of the good functional results achieved and low complication rate. The procedure was easy to perform because of the short duration and could be repeated frequently without significant additional risks.