Objective To explore the clinical value of testing the contents of soluble Delta-like-ligand 1 (DLL1) in cerebrospinal fluid (CSF) and serum in the early diagnosis of tuberculous meningitis (TM). Methods This study enrolled 110 patients with infectious disease of central nervous system (CNS) who had been treated in our department from December 2008 to March 2011.They were sorted into 4 groups: 50 subjects with tuberculous meningitis in group TM, 30 subjects with viral meningitis in group VM, 20 subjects with purulent meningitis in group PM, and 10 subjects with cryptococcal meningitis in group CM.Another 30 healthy subjects were enrolled as controls.ELISA was applied to measure the soluble DLL1 contents in both CSF and serum in subjects of all groups after hospitalization. The DLL1 levels in CSF were observed in group TM at different time points posttreatment to analyze their associations with CSF protein and cell population. Results The mean.contents ofDLL1 (ng/mL) in both CSF and serum in group TM were significantly higher than in all the other groups (P＜0.05).There were no significant differences in the mean content of DLL1 (ng/mL) in either CSF or serum among groups VM,PM,CM and control (P＞0.05).The CSF DLL1 content in the 14improved TM patients significantly decreased from 2 to 4 to 6 weeks posttreatment (P＜0.05) while the CSF DLL1 content in the 4 deteriorated patients significantly increased from 1 to 2 (4) to 6 weeks posttreatment (P＜0.05). Conclusion Since the contents of soluble DLL1 in both CSF and serum will significantly increase in TM patients,testing the contents of soluble DLL1 in CSF and serum may have a significant value in the early differential diagnosis of TM.