In spite of the adequate therapy serious inflammatory complications affect the majority of preterm neonates. Recently, the role of fetal inflammatory response syndrome has been emerged as a possible mechanism. This new clinical entity is characterised by the generalised activation of fetal immune system which is often the result of chorioamnionitis. The level of inflammatory cytokines (interleukin-6) often elevates in fetuses affected by this syndrome. Elevated cytokine levels induce the infiltration of inflammatory cells into the amnion and activate matrix metalloproteases in the fetus. As a result, preterm birth occurs. The high levels of inflammatory cytokines in the fetus are associated with the development of bronchopulmonary dysplasia and periventricular leukomalacia in the newborn. Except the elevation of fetal interleukin-6 levels there is still no specific clinical or laboratory sign of the fetal inflammatory response syndrome. Further investigation is needed to understand the importance of this syndrome in the development of perinatal complications and to develop specific laboratory tests for the early recognition.