Background: Open surgical cricopharyngeal myotomy(CM) is considered standard of care for Zenker's diverticulum(ZD). Trans-oral CM has been described using a rigid stapling device for two decades; however, this remains problematic for severely kyphotic patients. This problem can be overcome with flexible endoscopy utilizing an electrosurgical needle knife. We sought to compare clinical outcomes between these techniques to stratify patient selection.Methods: Patients undergoing ZD treatment from 1992 to 2015 were reviewed. Demographics, diverticulum size, post-operative complications, and length of stay (LOS) were compared between open cricopharyngeal myotomy (OpenCM), rigid trans-oral stapling myotomy (RigidCM), and flexible endoscopic myotomy (FlexCM). Dysphagia scores (DS, 0:best-4:worst) and pneumonia incidence were assessed pre-operatively and post-operatively.Results: 62 patients underwent OpenCM (39/62(63 %)) or endoscopic CM (23/62(37 %) (8 RigidCM/15 FlexCM)). CM significantly reduced dysphagia for all approaches [OpenCM:2(2-3)-0(0-0); RigidCM:2(2-2)-0(0-0); FlexCM:3(3-3)-0(0-0)]. FlexCM patients had significantly worse pre-operative DS. Endoscopic CM was attempted and completed in 23/35(66 %) patients. Reasons for OpenCM conversion included inability to position the diverticular retractor due to patient body habitus (RigidCM), and the inability to position the overtube due to small ZD (FlexCM). Major post-operative complications were rare and similar in all groups. Medium-to-long-term post-myotomy pneumonia was comparable between groups. LOS (days) was reduced for FlexCM (1(1-2)) versus RigidCM (3(2-6)) and OpenCM (4(3-7)).Conclusions: CM is highly effective for treating ZD. Open and endoscopic approaches offer comparable outcomes and dysphagia resolution. FlexCM is efficacious for large ZD and can be performed in most patients irrespective of body habitus. FlexCM represents an excellent approach for large ZD, while OpenCM should be reserved for small ZD for which an overtube cannot be positioned.