Twenty patients with the diagnosis of Zenker's diverticulum were studied clinically and manometrically. In 8 patients oropharyngeal clearance of liquid isotopic markers was done. In three, esophageal emptying of a marked meal was also studied. Clinically, sixteen patients had oropharyngeal dysphagia, while for remained asymptomatic. Dysphagia was severe in only five patients. In half of the patients there were signs of hiatus hernia and/or reflux. Pharyngo-sphincteric incoordination was present in 70% of cases with a mean resting pressure of the LES significantly lower than in controls. There were no differences among patients with or without reflux. Isotopic esophageal clearance was not useful as a test, as there were no significant differences with the control group. On the other hand, esophageal emptying of solid isotopic meals may show the persistence of food in the diverticular sac long time after the meal.