Objective To explore the effects of balloon dilatation on esophageal motility in patients with achalasia. Methods Forty eight patients were diagnosed as having achalasia by clinical features, barium radiography, endoscopy and esophageal manometry (PC polygraf HR, Medtronic). The following parameters were evaluated: the symptom score, the maximal width of the esophagus (MWE) on barium radiography, lower esophageal sphincter pressure (LESP), lower esophageal sphincter relaxation rate (LESRR) and the contraction amplitude of esophageal body before and after dilatation at 4 weeks and 12～24 weeks. Results (1) Parameters of symptom score and the maximal esophagus width were significantly decreased ( P