Fifteen autopsy cases who died within 20 days after intravariceal endoscopic injection sclerotherapy using 5% ethanolamine oleate were examined to clarify the planar extent of thrombi. In 11 of the 15 cases, thrombi extended to part of the fundus of the stomach, as well as the lower esophagus. In addition to these cases, six autopsy cases who survived more than a month after the first injection were studied for the extent of thrombi on the basis of the angioarchitectural characteristics of esophageal varices. The extent could be divided into 3 groups: Group 1 included 5 cases with thrombosis in the main trunk of the varix alone, which connected with longitudinal veins (so-called “Venetian blind-like or sudare-like veins”) running for 3–4cm upward from the esophago-gastric junction. Group 2 included 9 cases with thrombosis in the main trunk and Venetian blind-like veins in the submucosa alone. Group 3 included 7 cases with thrombosis in the main trunk and Venetian blind-like veins in both the submucosa and lamina propria. These results obtained may provide basic information concerning this treatment. Furthermore, the mechanism of the recurrence of varices after eradication induced by treatment was discussed on the basis of the results.