introduction. a great variety of cytokines are produced locally in the central nervous system in response to microbial infection, and their levels have been used as a diagnostic parameter of infection. objectives: to determine the concentrations of interleukin- 6 (il- 6) in cerebrospinal fluid (csf) of newborns with bacterial meningitis and the effectiveness of the determination as a diagnostic tool. material and methods. this was a prospective study from december 2002 to july 2003, in the instituto nacional de perinatologia (inper), in which the concentrations of il- 6 in the csf were measurered in newborns with a clinical diagnosis of sepsis. results. fourteen out of 58 newborns attended during the study period had bacterial meningitis.the mean il- 6 concentration in the meningitis group was 9 994 pg/ml vs 15.4 pg/ml in the control group (p <0.05). sensitivity was (92%),the specificity (100%);the positive predictive value and area under the roc curve support that il- 6 concentration of >50 pg/ml in csf are the cut- off level of neonatal bacterial meningitis. the concentrations of il- 6 in the csf were greater, demonstrating itself that concentrations of il- 6 equal or greater to 50 pg/ml have a sensitivity of 92% and a specificity of 100%, for the diagnosis of bacterial meningitis. conclusions. the determination of the concentration of il- 6 in csf could be a useful tool in the meningitis diagnosis; however csf conventional analysis and culture are still the gold standard.