A retrospective study carried out on 74 patients among 101 consecutive cases of achalasia of the esophagus operated from 1967 to 1989 is reported. On 21 patients observed between 1967 and 1975, a standard transabdominal Heller cardiomyotomy was performed (group A). From 1976 to 1989, the treatment of choice was a Heller myotomy associated with a modified Dor's fundoplication. In 80 consecutive cases (group B) the extension of myotomy was regulated by intraoperative monitoring of lower esophageal sphincter pressure. A 5-year follow-up with questionnaires, physical examination, and barium swallows was carried out on 16 patients in group A and on 58 patients in group B. In 75.6% of the cases (56 patients) follow-up examinations included esophageal manometry and 24-hour esophageal pH monitoring. Recurrence of dysphagia was recognized in 3 cases in group A (18.7%) and in 2 cases in group B (3.4%) (P = 0.053); postoperative gastroesophageal reflux, measured as a percentage of total reflux time, showed a significantly lower mean value in group B than in group A (1.8% vs. 4.1%, P < 0.01). This study suggests that an anti-reflux procedure lowers postoperative gastroesophageal reflux after Heller myotomy. Due to the low incidence of postoperative reflux and the negligible recurrence of dysphagia, Heller myotomy associated with a modified Dor's fundoplication may represent the surgical treatment of choice for achalasia of the esophagus.