Nonspecific esophageal motility disorder (NEMD)is a vague category used to include patients with poorlydefined esophageal contraction abnormalities. Thecriteria include “ineffective” contractionwaves, ie, peristaltic waves that are either of lowamplitude or are not transmitted. The aim of this studywas to identify the prevalence of ineffective esophagealmotility (IEM) found during manometry testing and to evaluate esophageal acid exposure andesophageal acid clearance (EAC) in patients with IEMcompared to those with other motility findings. Weanalyzed esophageal manometric tracings from 600consecutive patients undergoing manometry in our laboratoryfollowing a specific protocol from April 1992 throughOctober 1994 to identify the frequency of ineffectivecontractions and the percentages of other motility abnormalities present in patients meetingcriteria for NEMD. Comparison of acid exposure and EACwas made with 150 patients who also had both esophagealmanometry and pH-metry over the same time period. Sixty-one of 600 patients (10%) met thediagnostic criteria for NEMD. Sixty of 61 (98% ) ofthese patients had IEM, defined by at least 30%ineffective contractions out of 10 wet swallows.Thirty-five of these patients also underwent ambulatoryesophageal pH monitoring. Patients with IEM demonstratedsignificant increases in both recumbent medianpercentage of time of pH 4 (4.5%) and median distal EAC (4.2 min/episode) compared to those with normalmotility (0.2%, 1 min/episode), diffuse esophageal spasm(0%, 0.6 min/episode), hypertensive LES (0%, 1.8min/episode), and nutcracker esophagus (0.4% 1.6 min/episode). Recumbent acid exposure inIEM did not differ significantly from that in patientswith systemic scleroderma (SSc) for either variable(5.4%, 4.2 min/episode). We propose that IEM is a more appropriate term and should replace NEMD,giving it a more specific manometric identity. IEMpatients demonstrate a distinctive recumbent refluxpattern, similar to that seen in patients with SSc. This finding indicates that there is anassociation between IEM and recumbent GER. Whether IEMis the cause or the effect of increased esophageal acidexposure remains to be determined.