This study evaluated the inner surface of esophageal masses using multidetector computed tomography (MDCT) after esophageal distention with an ingested effervescent powder without inducing pharmacological esophageal hypotonia. From September 2004 to December 2005, 38 patients underwent MDCT after esophageal distention using only an effervescent powder that was ingested only 35 s after injecting the contrast agent and twice 50 s after the injection. Ten patients had a normal esophagus and twenty-eight patients had an esophageal mass detected by endoscopy. The degree of distention at three levels (upper, middle, and lower) and the intraluminal surface of the esophageal mass were evaluated. The surface between the normal and esophageal mass were analyzed using an ANOVA test. Esophageal distention in the upper and middle thirds was classified as either "good" or "fair" in 90.8% of cases. In the lower third, 81.6% of cases were either "good" or "fair". All esophageal cancers had an irregular surface but all normal lining and benign esophageal masses had a smooth surface. MDCT after esophageal distention using the effervescent powder ingested twice achieved good-to-fair distention in the esophagus, and is a useful diagnostic modality for identifying the intraluminal surface of esophageal masses.