This study investigates the effect of a single dilation on the morphology of the lower esophageal ring and on the clinical course of symptomatic patients. Thirty-three patients were studied prospectively for a mean period of 24.3 +/- 19.2 months. Passage of a large bougie (46-58 F) resulted in a rupture of the ring in each instance and its mean diameter increased from 11.4 +/- 3.6 to 17.2 +/- 4.1 mm. No complications occurred, and all patients were symptom-free at the first follow-up examination four weeks after dilation. However, late symptomatic recurrences were frequent. After one year, the estimated proportion of patients remaining free of symptoms was 68% after two years 35%, and after five years 11%. Repeated treatments were performed with similar ease and effectiveness; again, no complications were encountered. Neither the initial ring size nor the presence or absence of esophagitis determined the likelihood of symptomatic recurrences. It is concluded that single dilations of symptomatic lower esophageal rings are safe, easily performed, and well tolerated. Long-term cure of episodic dysphagia is rare, but recurrences can be successfully treated by repeated dilations.