Zenker diverticulum (named after German pathologist Friedrich Albert von Zenker) is an acquired diverticulum of the pharynx. It is a pulsion diverticulum, resulting from dyscoordination of upper oesophagal sphincter peristalsis and subsequent herniation of the oesophagal mucosa and submucosa. It is therefore not functional pharyngeal/oesophagal anatomy. The diverticulum occurs through Killian's triangle, along the midline, the weakest portion of the hypopharyngeal musculature.

A Zenker diverticulum characteristically projects posteriorly, in the prevertebral soft tissues. This diverticulum, because of its mass effect, can cause difficulty with breathing and dysphagia and can lead to regurgitation and halitosis.

These can be treated surgically.