The major purpose of this investigation was to describe the causes, possible complications, and prognoses of horses with esophageal obstruction. Of 34 cases presenting with esophageal obstruction, 28 cases were due to impaction of ingesta. Obstruction due to pre-existing esophageal disease occurred in 4 horses with megaesophagus, in 1 horse with stricture in the upper third of the esophagus, and in 1 horse with esophageal diverticulum. There was no significant difference in the contamination of the trachea between horses that subsequently developed aspiration pneumonia and those that did not. The duration of esophageal obstruction prior to admission was significantly longer in horses that developed aspiration pneumonia (median 18, range 2-48 h) than in those horses that did not (median 4, range 0.5-48 h). Although the obstruction was relieved in all 34 horses, 4 were euthanized because of recurring obstruction due to megaesophagus (n = 2), esophageal diverticulum (n = 1), and esophageal stricture (n = 1).