Achalasia is the most recognized esophageal motor disorder first described 300 years ago by Sir Thomas Willis. Although the cause of achalasia remains unknown, the disease is thought to occur as a result of degeneration of Auerbach's plexus in the intramural nervous network. A review of the literature reveals that there is reversibility of this disease in some patients after treatment, raising intriguing questions as to the pathogenesis of this disorder and underscoring the need for further study.