PURPOSE: To evaluate whether there is any difference in thickness of the distal esophageal wall in various examination conditions including at rest, during Valsalva maneuver and after drinking cold water and to search the optimal condition for transabdominal US examination in diagnosis of esophageal varix. MATERIALS and METHODS: Transabdominal ultrasonography was prospectively performed in forty one patients with esophageal varix confirmed by endoscopy and underlying liver. The thickness of the anterior distal esophageal wall was measured three times consecutively and calculated the mean thickness at rest, during Valsalva maneuver and following drinking cold water. At the same time, the normal control group consisted of forty four normal patients, and the mean thickness was calculated in the same method to established the normal value. Data obtained by both measures were compared and analyzed by ANOVA and Tuckey multiple comparison. RESULTS: The mean thickness of the distal esophageal wall in variceal group was 5.20 +/-.82 mm at rest, 6.07 +/-2.01 mm during Valsalva maneuver, 4.07 +/-.61 mm following drinking cold water. The mean thickness of the esophageal wall increased during Valsalva maneuver and decreased following drinking cold water when compared to the mean thickness at rest. There was a statistically significant difference in the mean thickness measured at rest, during Valsalva maneuver and following drining cold water among each grade of esophageal varix, grade I(n=19), grade II(n=10), grade III(n=12) (p=0.00, p=0.01, and p=0.01, respectively). Meanwhile, the mean thickness of the normal control group was 2.74 +/-.74 mm at rest, 3.46 +/-.00 mm during Valsalva maneuver, and 2.29 +/-.65 mm following drinking cold water(p=0.00). CONCLUSION: In order to accurately diagnose esophageal varix and to estimate grade using transabdominal ultrasonography, the maintenance of the same examining condition is essential, and the measurement done at rest appears to be the optimal condition for the examination.