This retrospective, study compared the efficacy and safety of Ibuprofen-Lysinate (Arfen, intramuscular formulation, Group I, n=156) used during 2000-2005 and Sodium-ibuprofen (Pedea, intravenous solution, Group II, n=60) used during 2006-2008, for the prophylaxis of Patent Ductus Arteriosus in inborn neonates with gestational age ≤ 28 weeks. Ductus closure rate after prophylaxis was significantly higher (73.1% vs 50%; P=0.002) and surgical ligation significantly lower (8.2% vs 23.3%; P=0.005) in Group I. A smaller number of neonates of Group I vs Group II showed oliguria and hemorrhagic disease.