During perinatal period, corticosteroid treatment has two major indications: first antenatally to improve fetal maturity and then to treat postnatal bronchopulmonary dysplasia. Antenatal corticosteroid treatment is widely proved to be efficient in reducing hyaline membrane disease and perinatal mortality incidence. Moreover, it has positive effects on intraventricular hemorrhage incidence, on hemodynamic failure, on persistent patent ductus arteriosus and on necrotizing enterocolitis. Side-effects are few and mild considering expected benefits and they usually occurs after multiple courses. Contra-indications are rare. Bronchopulmonary dysplasia comes with early, important and prolonged inflammatory processes. Corticotherapy allows decreasing significantly length of mechanical ventilation and oxygenotherapy among ventilated premature infants diagnosed with bronchopulmonary dysplasia. In the meantime, acute side-effects are frequent and benefits on mortality rate and long term outcome are not obvious. Main concern remains on possible long-term deleterious consequences on growth, lung and central nervous system development. In this field, clinical data are still insufficient as animal experimentation data promote caution and search for a minimal efficient therapeutic pathway.