To determine the value of endoscopy, manometry, and scintigraphy in predicting the severity of achalasia, 25 patients with primary achalasia of the esophagus were posprectively studied; 17 patients could be examined prior and post pneumatic dilatation. According to the symptoms, the severity was graded from I to IV. While endoscopic findings did not well correlate with the symptom score, the lower esophageal sphincter pressure and the resting pressure in the esophageal body were significantly correlated with the severity of the disease (p less than 0.01). The esophageal retention of radioactivity rose parallel to the symptom score (p = 0.07). Both manometric and scintigraphic findings changed significantly after therapy (p less than 0.01). Manometry and scintigraphy of the esophagus can be used to measure treatment related effects in patients with primary achalasia. Endoscopic findings are not related to subjective complaints, but an endoscopic examination should always be performed to exclude malignancies of the esophago-gastric junction.