Background: As clinical signs of EOBI and NBI are unspecific, a sensitive and specific laboratory tool is needed for the diagnosis .Aim: To evaluate IL-8 as a marker for presumed EOBI or NBI .Subjects/method: IL-8 and CrP were evaluated on admission in 257 neonates (22-42 weeks of gestation) with clinical signs of EOBI or a history of amniotic infection and 125 times beyond the first week of lifeat the onset of clinical symptoms suggesting NBI in 59 PI (23-35 wk. Gest.). The diagnosis of infection was based on the presence of clinical symptoms and either a positive blood culture or a CrP > 10mg/1 at 24 - 48 hrs after the first blood sample. Results: At cutoffs of IL-8 > 70 pg/ml and CrP > 10 mg/1 sensitivities (Se.) and specificities (Sp.) are shown for IL-8, CrP and the combination of IL-8 > 70pg/ml and/or CrP > 10mg/1. EOBI: Se.: 71%, 40%, 86%, Sp.: 78%, 98%, 78%,. Positive Predictive Value for EOBI: 42%, 86%, 47%. NBI: Se.: 76%, 41%, 88%. Sp.: 92%, 98%, 89%. PPV for NBI: 73%, 85%, 72%. Conclusion: The combination of IL-8 and CrP is a sensitive and specific test for the early diagnosis of both EOBI and NBI in neonates.