Twenty-seven patients were treated with a Heller myotomy and Dor fundoplication; some peristaltic contractions occurred in seven after operation. When clinical, radiological and manometric data in the seven patients developing peristalsis were compared with findings in the other 20, there were no differences in symptoms, lower oesophageal sphincter pressures and lengths, relief of dysphagia or oesophageal calibre reduction. Oesophageal resting pressure was lower and oesophageal contraction amplitudes were statistically higher in patients with restored peristalsis, which correlated only with the amplitude of contractions 5 cm above the lower oesophageal sphincter (P < 0.05, 95 percent confidence interval). Peristaltic contractions probably exist before treatment, but are concealed by the dilated oesophagus and the common cavity phenomenon. Achalasia is not necessarily associated with complete aperistalsis. No difference was found in the outcome of surgical treatment, and the return to peristalsis appears to be clinically relevant.