Compared with classic achalasia, vigorous achalasia has been defined as achalasia with relatively high esophageal contraction amplitudes, often with minimal esophageal dilation and prominent tertiary contractions on radiographs, and with the presence of chest pain. However, no study using current manometric techniques has compared manometric, radiographic, and clinical findings in vigorous and classic achalasia or questioned the usefulness of making this distinction. Fifty-four cases involving patients with achalasia whose radiographic and manometric studies were performed within 6 months of each other were available for review. Patients with vigorous achalasia (n = 17), defined by amplitude greater than or equal to 37 mm Hg, and patients with classic achalasia (n = 37), defined as amplitude less than 37 mm Hg, had substantial overlap in radiographic parameters of esophageal dilation, tortuosity, and tertiary contractions. Manometric properties of repetitive waves and lower esophageal sphincter pressure and clinical aspects of chest pain, dysphagia, heartburn, and satisfactory responses to pneumatic dilation were similar in both forms of achalasia. A separate analysis of patients with mean contraction amplitude greater than 60 mm Hg revealed similar findings. It is concluded that use of amplitude as a criterion for classifying achalasia is arbitrary and of dubious value.