In Japan, the results of histopathologic analyses on esophageal carcinomas have shown that almost all of them are squamous epithelial cancers. The abnormal epithelium that is difficult to differentiate by endoscopy can be easily visualized by chromoendoscopy with the use of iodine staining. Since the establishment of endoscopic mucosal resection (EMR), it has been used increasingly to treat mucosal cancers. It is necessary to diagnose accurately the depth of invasion of mucosal cancer when it is to be treated by EMR. In this article, we explain our routine techniques to visualize and interpret the lesions that are candidates for EMR. It is of great benefit to detect lesions at their early stage, which leads to the most desirable endoscopic treatment.