Nine patients, all with symptoms of dysphagia and/or substernal chest pain, are described. In 5, radiologic studies of the esophagus were normal, and in none was there an increase in esophageal caliber. Each patient had dysfunction of the lower esophageal sphincter, as assessed by manometry, the chief abnormality being impairment of relaxation in 7, and derangement of contraction in 2. All showed peristaltic activity in the esophageal body during manometric studies. One patient had the classic manometric pattern of diffuse esophageal spasm. In the remainder, some but not all of the manometric features of this disorder were present. These observations serve to emphasize that the boundaries between achalasia, diffuse esophageal spasm, and other less well-characterized disorders of esophageal motility are blurred; and they are consistent with the view that such disorders represent parts of a continuous spectrum.