Infants with birth weight at <1200gm and/or <28 weeks gestation who have been diagnosed with a Patent Ductus Arteriosus (PDA) qualify for the study if there are no contraindications to treatment. Infants are randomized into treatment arms of <96 hrs old and >96 hrs old. Ibuprofen is given in the dosage of 10 mg/kg on initial dose, followed 24 hours later by 5 mg/kg dose and then 24 hours later another dose of 5 mg/kg. An echocardiogram will be done prior to treatment and then within 48 hours after treatment.