Our aim was to assess the efficacy and safety of intravenous (i.v.) paracetamol vs. i.v. ibuprofen for the treatment of hemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants. This is a multicenter randomized controlled study. Infants with a gestational age of 25+0-31+6 weeks were randomized to receive i.v. paracetamol (15 mg/kg/6 h for 3 days) or i.v. ibuprofen (10-5-5 mg/kg/day). The primary outcome was the closure rate of hsPDA after the first treatment course with paracetamol or ibuprofen. Secondary outcomes included the constriction rate of hsPDA, the re-opening rate, and the need for surgical closure. Fifty-two and 49 infants received paracetamol or ibuprofen, respectively. Paracetamol was less effective in closing hsPDA than ibuprofen (52 vs. 78%; P = 0.026), but the constriction rate of the ductus was similar (81 vs. 90%; P = 0.202), as confirmed by logistic regression analysis. The re-opening rate, the need for surgical closure, and the occurrence of adverse effects were also similar.Conclusions: Intravenous paracetamol was less effective in closing hsPDA than ibuprofen, but due to a similar constriction effect, its use was associated with the same hsPDA outcome. These results can support the use of i.v. paracetamol as a first-choice drug for the treatment of hsPDA.Trial registration: Clinicaltrials.gov : NCT02422966, Date of registration: 04/09/2015; EudraCT no: 2013-003883-30. What is Known: • The successful closure of patent ductus arteriosus with oral paracetamol has been recently reported in several preterm infants, but only one randomized controlled study investigated the efficacy of intravenous paracetamol. What is New: • Intravenous paracetamol is less effective in closing hsPDA than ibuprofen, but have a similar constriction effect. • These results can support the use of i.v. paracetamol as a first-choice drug for the treatment of hsPDA.