ObjectiveTo evaluate the blue laser imaging（BLI） magnifying endoscopy combined with endoscopic submucosal dissection （ESD） in diagnosis and treatment of low grade intraepithelial neoplasia detected by normal endoscopic biopsy. MethodsA total of 76 patients were diagnosed as having LGIN by preoperative biopsy. But 3 months later， BLI endoscopic re-examination showed that the lesions did not heal or even worsened. Patients who received ESD therapy were included in the retrospective study during January 2014 to January 2016 in Remin Hospital of Wuhan University. The efficacy and complications of ESD， and the consistence rate of diagnosis between general endoscopic biopsy， BLI magnifying endoscopy and pathologic diagnosis of total tumor after ESD were analyzed. ResultsThe complete resection rate and curative rate of ESD were 100.0％ （76／76） and 97.4％ （74／76） respectively. The incidences of hemorrhage and perforation during the operation were 3.9％ （3／76） and 1.3％ （1／76）， and there was no delayed bleeding or perforation. The consistence rates of diagnosis of common endoscopic biopsy and BLI were 55.3％ （42／76） and 92.1％ （70／76） respectively， with significant difference （χ2=51.987， P＜0.001）. ConclusionLow-grade intraepithelial neoplasia of the upper digestive tract may be easily underestimated by ordinary endoscopy biopsy. For these underestimated “low-grade intraepithelial neoplasia”lesions， ESD can not only be used to confirm the diagnosis， but also give safe and effective treatment. The examination of BLI combined with magnifying endoscopy is recommended before ESD， because BLI endoscopy classification of the lesions has positive effects on ESD of upper gastrointestinal mucosa lesions.