Chorioamnionitis is the inflammatory response to an acute inflammation of the membranes and chorion of the placenta. We provide a critical review of the relationship between chorioamnionitis and the risk of prematurity and adverse maternal-fetal outcome. Chorioamnionitis results as a major risk factor for preterm birth and its incidence is strictly related to gestational age. It is associated with a significant maternal, perinatal and long-term adverse outcomes. The principal neonatal complications are neonatal sepsis, pneumonia, bronchopulmonary dysplasia, perinatal death, cerebral palsy and intraventricular hemorrhage. The role in neonatal outcome is still controversial and more conclusive studies could clarify the relationship between chorioamnionitis and adverse neonatal outcome. Maternal complications include abnormal progression of labour, caesarean section, postpartum hemorrhage, abnormal response after use of oxytocin and placenta abruption. Prompt administration of antibiotics and steroids could improve neonatal outcomes.