The most common esophageal motility abnormality in patients with noncardiac chest pain is nutcracker esophagus. Most investigators regard nutcracker esophagus as a diffuse process involving the distal esophagus. Others consider it a segmental disturbance affecting isolated regions of the distal esophageal smooth muscle. This study compared the prevalence, clinical features, consistency, and manometric course of patients with either segmental high-amplitude peristaltic contractions (SHAPC) or those with the traditional diffuse contraction abnormalities termed nutcracker esophagus (NE). We particularly sought to determine whether patients with SHAPC represent an early spectrum evolving into a more diffuse contraction disorder--NE. The prevalence and clinical features of patients with either motility disturbance were similar. Thirty-nine percent of our patients had abnormally high peristaltic amplitude in locations of the proximal esophagus not previously described. Follow-up manometric studies demonstrated that only 53% of patients in the NE and 20% with SHAPC retained the same manometric diagnosis. In addition, 33% of patients in the NE group and 40% of the SHAPC group permutated into each other. These findings indicate that patients with SHAPC do not represent an early process subsequently evolving into a more diffuse contraction abnormality. Rather, the motility pattern of high-amplitude peristaltic contractions--segmental or diffuse--constitutes a labile marker associated with noncardiac chest pain.