Prophylactic indomethacin reduces patent ductus arteriosus (PDA) and intraventricular hemorrhage in very low birth weight infants. However, the effects of early indomethacin on long-term neurodevelopment remain uncertain. There is also insufficient evidence to rule out serious adverse effects, such as increases in the risk of necrotizing enterocolitis (NEC) and retinopathy of prematurity (ROP). The aim of this trial was to determine if prophylactic administration of indomethacin improves survival without neurosensory impairments in extremely-low-birth-weight infants. Infants (n=1202) with birthweights 500 to 999 grams were randomized between 2 and 6 hours after birth to receive either intravenous indomethacin (0.1 mg/kg) or equal volumes of normal saline placebo, daily for 3 days. The primary outcomes at a corrected age of 18 months was a composite of death, cerebral palsy, cognitive delay, deafness, or blindness. Secondary long-term outcomes were hydrocephalus necessitating the placement of a shunt, seizure disorder, and microcephaly. Secondary short-term outcomes were patent ductus arteriosus, pulmonary hemorrhage, chronic lung disease, cranial ultrasonographic abnormalities, nectrotizing enterocolitis and retinopathy. Infants were evaluated in follow-up at 18-22 months corrected age.