OBJECTIVE: To determine the accuracy of adenosine deaminase (ADA) measurements in the diagnosis of tuberculous meningitis (TBM). DESIGN: After a systematic review of English language studies, the sensitivity, specificity and accuracy of ADA concentrations in the diagnosis of cerebrospinal fluid (CSF) were evaluated using random effects models. Summary receiver operating characteristic curves were used to summarise overall test performance. RESULTS: Ten studies met our inclusion criteria. The sensitivity of ADA in the diagnosis of TBM was 0.79 (95%CI 0.75-0.83), specificity 0.91 (95%CI 0.89-0.93), positive likelihood ratio 6.85 (95%CI 4.11-11.41), negative likelihood ratio 0.29 (95%CI 0.19-0.44) and diagnostic odds ratio 26.93 (95%CI 12.73-56.97). CONCLUSION: Our data suggest that ADA in the CSF can be a sensitive and specific target and a critical criteria for the diagnosis of TBM. © 2010 The Union.