The purpose of this study was to analyze the influence of antenatal glucocorticoid therapy (AGT) on mortality and chronic lung disease (CLD) in surviving preterm infants 23 to 28 weeks gestational age (WGA). This was a multicenter, prospective, observational study. A total of 2448 infants 23 to 28 WGA were born in 2002 to 2003; 27.7% did not receive AGT, 18.8% were exposed to partial AGT, and 53.5% were exposed to complete AGT. A total of 883 died and 22.9% of 1537 survivors were affected by CLD. Unadjusted univariate analysis showed AGT was associated with a reduction in mortality (p<0.001), either with partial or complete AGT courses, and also with a reduction in CLD in survivors (p<0.001), but only with complete AGT courses. In logistic regression analysis adjusted for confounding factors and a propensity score for AGT, AGT was significant and independently associated with a reduction of mortality, but only for complete AGT course (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.47 to 0.87; p=0.004), and with a decrease in CLD if a complete AGT course was administered (OR, 0.63; 95% CI, 0.45 to 0.89; p=0.009). A complete course of AGT in 23 to 28 WGA pregnancies is associated with decreased rates of neonatal mortality and CLD disease in surviving infants.