['The chitinase 3-like 1 (CHI3L1) has an important role in cancer progression, and high CHI3L1 expression is associated with the development and progression of cancers. Previous studies had been controversial with respect to the association between CHI3L1 expression and lung cancer prognosis. Thus, we performed a meta-analysis to investigate the prognostic value of CHI3L1 expression in lung cancer.', 'We searched Pubmed, Embase, and Wanfang databases to identify eligible studies. Overall survival and disease free survival were collected from included studies. Pooled hazard ratios (HRs) with 95% confidence interval (95%CI) were calculated to estimate the association. Seven studies comprising 911 lung cancer patients were included in this meta-analysis.', 'The results showed high CHI3L1 expression was independently associated with poorer overall survival in lung cancer patients (HR = 1.71, 95%CI 1.24-2.37, P = 0.001). Subgroup analysis by histological type showed that high CHI3L1 expression was independently associated with poorer overall survival in both non small-cell lung cancer patients (HR = 2.23,95%CI 1.43-3.47, P < 0.001) and small-cell lung cancer patients (HR = 1.45, 95%CI 1.06-2.00, P = 0.021). In addition, sensitivity analysis by omitting single study by turns did not change the pooled outcomes obviously.'] Is elevated Serum Concentration of Chitinase 3-Like 1 an Independent Prognostic Biomarker for Poor Survival in Lung Cancer Patients?