ROC curves demonstrated that serum YKL-40 has a sensitivity of 72.70%, a specificity of 84.13% and an AUC of 0.874 for the diagnosis of ESCC, which was superior to CEA (Sen: 8.00%; Spe: 96.80%, AUC = 0.652), CYFRA21-1 (Sen: 40.00%; Spe: 92.06%, AUC = 0.746) and SCCA (Sen: 32.67%; Spe: 94.44%, AUC = 0.789). Here, CHI3L1 is linked to esophageal squamous cell carcinoma.