Sixteen patients (nine male) underwent perendoscopic pneumatic dilatation for achalasia. The Witzel dilator was chosen as it allows placement of the balloon under endoscopic vision. Its efficacy was assessed using esophageal scintigraphy. Symptom score and esophageal transit values at 100 s and after a drink of water all improved significantly (P less than or equal to 0.014) after dilatation and there was a significant correlation between the improved symptom score and the change in transit values after 100 s (r = 0.586, P = 0.017). At follow-up at 8 (3-16) months [mean (range)], 15 of 16 patients (94%) are symptom free. The Witzel dilator is effective in the treatment of achalasia. Esophageal scintigraphy offers a quantitative assessment of esophageal function, helping the clinical investigator evaluate new forms of therapy.