Interleukin-6 and interleukin-8 as useful parameters for the early diagnosis of neonatal bacterial infection. Objective: to determine whether interleukin-6 (IL6) or interleukin-8 (IL8) is the best marker of a bacterial infection in newborn babies (BINB) within the first 12 hours of life, when the C-reactive protein (CRP) is not yet incresed. Mehod: the IL6 and IL8 were measured in emergency using a chemiluminescent technique on Immulite (DPC, France), in cord blood or serum of newborn babies of less than 12 hours of life. The fetomaternal inclusion criteria were: 1) at child birth, a premature rupture of the membranes (before 37 weeks of amenorrhea (WA)); a prolonged rupture of the membranes (more than 12 hours before child birth); a maternal fever during the week before child birth (≥ 38 °C rectal); a maternal fever during the labor (≥ 38 °C rectal); an urinary maternal infection during the 15 days before child birth; a premature birth (< 37 WA); 2) at the arrival in the department of paediatrics neonatology (newborn childs of less than 12 hours of life): clinical signs in favour of infection. Only the cases with initial CRP level normal (< 5 mg/L in cord blood or serum) were considered. The level of CRP was followed at 24 and 48 hours after birth. 246 cases have been adopted according to the various clinical and/or biological criteria, and divided into three groups: group 1 (non infected: 211 cases), group 2 (ambiguous: 10 cases) and group 3 (infected: 25 cases). Receiver operating curves (ROC) have been established for each marker, alone or combined, in order to determine the bet cut-off value for the diagnosis of bacterial infection (group 1 versus group 3). Results: with a cut-off value of 100 pg/mL, IL6 and IL8 in cord blood show respectively, versus CRP at 24 hours of life (cut-off at 10 mg/L), a sensitivity of 72 and 48 % / 76 %, a specificity of 95 and 96 % / 96 %, a negative predictive value (NPV) of 93 and 91 % / 95 %, a positive predictive value (PPV) of 58 and 55 % / 58 %. The combination of IL6 in cord blood and CRP at 24 hours of life shows a NPV of 98 % and a PPV of 45 %. Conclusion: IL6 and IL8, because of their high NPV, are at birth a precious help for the diagnosis of exclusion of BINB, and with the PPV, a good help also for the diagnosis of BINB, generally 24 hours before the CRP being positive. However in our hospital, the IL6 is preferred to IL8, the latter seeming to be affected by unknown non specific perinatal stimulations. The association IL6 at birth and CRP at 24 hours of life has an excellent exclusion value for BINB, and allows to reduce the impact of antibiotic treatments on bacterial ecology and health costs.