Sepsis causes 26% of these deaths and much of this are related to the immune response of the newborn (NB) against infections. This research was conducted in a NICU and was designed to evaluate the inflammatory response of 31 NB with bacterial sepsis through serial measurements of cytokines pro- inflammatory (TNF-?, IL-1? and IL 6), anti- inflammatory ( IL-10 and IL-1Ra) and C-reactive protein (CRP). Infants with sepsis were classified into two groups according to the evolution of the infection, sepsis group for those who presented a positive outcome and severe sepsis group, the NB with unsatisfactory outcome such as septic shock, disseminated intravascular coagulation, multiple organ failure and death. Cytokines analyzed were effective in the diagnosis and also for predict the degree of severity, mainly with regards to cytokines IL-6 and IL-1Ra. The homeostatic equilibrium/imbalance was correlated to the type of disease outcome: sepsis with no complication versus severe sepsis. This research shows an important part of the immune response of the NB, which should be known by medical assistants who take care of the seriously ill NB.