Diffuse esophageal spasm is an uncommon motility disorder that is found in less than 5% of patients undergoing esophageal motility testing for dysphagia. It is defined manometrically by the presence of 20% or more simultaneous contractions in the distal esophageal body with normal peristalsis. This motility abnormality has been traditionally identified as occurring primarily in the smooth muscle portion of the distal esophagus yet, the term "diffuse" persists in the medical literature to identify DES. The aim of our study was to assess the diffuse or limited nature of this entity by evaluating the prevalence of simultaneous contractions in both proximal and distal esophagus in patients with DES. We reviewed esophageal motility tracings of 53 consecutive patients (32 F, 21 M) with DES and compared them with 53 age-matched patients with manometric normal studies. In the distal esophagus we found 195 simultaneous contractions (37% of swallows) with a median of 3 and range of 2-7 per patient. Of the 53 patients with DES a total of 13 simultaneous contractions (2% of swallows) occurred in the proximal esophagus with only 3 (5.6%) of the 53 patients having 2 or more simultaneous contractions in 10 swallows. None of the patients with normal manometry showed more than one simultaneous contraction in either proximal or distal esophagus. In conclusion, these findings suggest that the term diffuse esophageal spasm is a misnomer and the DES is more appropriately described as "distal" esophageal spasm.