ObjectiveTo evaluate the application of modified LundKennedy (MLK) endoscopic scoring system in chronic rhinosinusitis (CRS).MethodsA prospective study was conducted. 51 patients suffering from CRS were included. Before operation, all patients received evaluation via visual analog scale (VAS), sinonasal outcome test22(SNOT22) and LundMackay CT score. During operation, their nasal endoscopic examinations were recorded. 3 months after surgery, all the patients were recalled for nasal endoscopic examination and their videos were saved. Meanwhile, they were asked to get VAS, SNOT22 and LundMackay evaluation again. All videos were scored by two rhinologists based on doubleblinded principle using three scoring systems: LundKennedy (LK) endoscopic score; discharge, inflammation, polyp (DIP) score and MLK endoscopic score. The scores were compared for testretest reliability, interrater reliability and their correlation with the existing subjective and objective scoring systems, as well as the surgical effect.ResultsIntraclass correlation coefficient (ICC) in testretest reliability and interrater reliability of MLK were higher than those of LK and DIP both before and after operation. At the same time, MLK was highly correlated to LK and DIP（r>0.79，P<0.01）. The correlation between MLK score and LundMackay CT score of preoperation（r=0.60, P<0.01）was higher than that of DIP score and LundMackay CT score. The postoperative MLK score showed significant correlation with VAS (r=0.30,P<0.05), but was lower than that LK score with VAS.ConclusionMLK endoscopic scoring system may be more suitable for clinical use because it is significantly associated with CT, LK and DIP scoring system, but its reliability is higher than theirs.