Esophageal achalasia is a benign esophageal motility disorder resulting from an impaired relaxation of the lower esophageal sphincter. The principles of treatment involve disruption of the sphincter at the esophagogastric junction. Treatment techniques include balloon dilatation, botulinum toxin injection, and surgical myotomy. In 2008, per-oral endoscopic myotomy (POEM) was introduced by Inoue et al. as an endoscopic myotomy with no skin incision. The procedure has been well accepted and widely applied owing to its minimal invasiveness and high cure rates. Moreover, there have been discussions on wider indications for POEM and new technical developments have been reported. The present article reviews the historical background and present status of POEM, as well as future prospects for its application in the treatment of esophageal achalasia.