A patient presented with chronic substernal discomfort and intermittent dysphagia for solids. High-resolution impedance manometry (HRIM) of the esophagus showed that there was no peristalsis in the esophageal body but incomplete relaxation of the lower esophageal sphincter and incomplete bolus transit, so the patient was diagnosed with achalasia. Moreover, probably because of esophageal stasis, eosinophilic infiltration that mimicked a pattern of eosinophilic esophagitis was observed, on the basis of multiple biopsies of the esophagus. The patient was given 50 mg prednisolone once daily; the symptoms improved dramatically, and HRIM showed complete recovery of esophageal peristalsis, deeper relaxation of the lower esophageal sphincter, and complete bolus transit profile. HRIM can therefore be used to assess dysmotility abnormalities in patients with achalasia and eosinophilic-like esophagitis, and steroids relieve these symptoms. Treatment with a high dose of prednisolone resulted in a complete disappearance of dysphagia because of improved esophageal motility and reduced eosinophilic infiltrate. It is therefore important to control the inflammatory process in patients with idiopathic achalasia, which is likely to result from an autoimmune reaction.