Objective To evaluate the clinical utility of interferon-gamma (IFN-γ) in serum and cerebrospinal fluid in the diagnosis of tuberculous meningitis .Methods IFN-γlevels in serum and cerebrospinal fluid were analyzed by ELISA method in 25 patients with tuberculous meningitis ,31 patients with viral meningitis and 12 patients with suppurative meningitis .Results The IFN-γlevels in cerebrospinal fluid were significantly higher in the patients with tuberculous meningitis (386 .3 ± 83 .5) ng/L than in the patients with viral meningitis (63 .4 ± 16 .2) ng/L or the patients with suppurative meningitis (116 .8 ± 22 .6) ng/L (P<0 .01) .The overlap was very small .In contrast ,the serum IFN-γ levels were very similar among the three groups (P>0 .05) .The sensitivity ,specificity and accuracy of IFN-γ level in cerebrospinal fluid for diagnosis of tuberculous meningitis were 92 .0% ,95 .3% and 94 .1% ,respectively .Conclusions Measurement of IFN-γlevel in cerebrospinal fluid may be helpful for the diagnosis of tuberculous meningitis .