['Maternal glucocorticoid (GC) treatment is widely used to prevent lung immaturity in preterm infants. There is growing evidence that GCs may be detrimental to the Central Nervous System (CNS). We investigated whether antenatal GC administration affects CNS function in a dose-dependent manner by measuring urine concentrations of a well-established brain damage marker, S100B.', 'We conducted a case-control-study in 70 preterm infants (1 GC vs 1 control) whose mothers received a complete GC-course (GC2, n=16), half-course (GC1, n=19), and controls (n=35). At four predetermined time-points, in the first 72 h from birth, we assessed S100B urine concentrations, using a commercially available immunoluminometric assay (Lia-mat Sangtec 100, AB Sangtec Medical, Bromma, Sweden). Data were correlated with primary neonatal outcomes (incidence of respiratory distress syndrome, length of ventilatory support and hospital stay, incidence of intraventricular hemorrhage, adverse 7th day neurological follow-up and neonatal death).', 'S100B in GC2 group at all monitoring time-points was significantly lower (P<0.01) than controls and GC1 group, while no differences (P>0.05) were evident between controls and GC1 group. No significant differences (P>0.05) were shown in primary outcomes between half or complete GC-course treated groups.'] Does antenatal glucocorticoid treatment affect preterm infants ' S100B urine concentration in a dose-dependent manner?