Over 900 patients have been treated at the Mayo Clinic for Zenker's diverticulum since 1944 using a one-stage transcervical diverticulectomy under general anesthesia. Overall results have been very good, but not entirely free of morbidity or mortality. An attempt is made to define those circumstances in which the procedures used have either been judgmentally or technically difficult or in which morbidity or mortality has occurred. These include patients with concomitant medical or surgical problems, or complexity related to the diverticulum itself. Among the latter are huge or giant sacs, patients with severe nutritional and respiratory symptoms related to aspiration, the perforated diverticulum, reoperation for recurrent diverticulum and cancer in a diverticulum.