Comparing PDA size before and after using intravenous paracetamol in premature infants with significant patent ductus arteriosus noticed: ductal diameter reduced significantly (3.43 ± 0.84 mm versus 2.53 ± 0.72 mm, p: 0.008) along with improving some other signs on echocardiography: left atrial dilatation, end-diastolic velocity left pulmonary artery > 0.2 m / s.