Background: Patent ductus arteriosus (PDA) is common in premature infants, especially in very low birth weight (VLBW) infants. Frequency of PDA is inversely related to gestational age. This is a cause that can lead to death because of complications, especially premature neonates. Objective: Define the rate and clinical features of tbe patent ductus arteriosus in premature infants. Describe the morphological and hemodynamic changes of the heart in premature infants with patent ductus arteriosus by echocardiography doppler. Patients and methods: included 159 premature infants are treated at the Pediatric Department of Hue Central Hospital from 5 /2010 to 5 /2011. All of them were performed clinical examination and echocardiography Doppler within 3 day after giving birth. Results: The patent ductus arteriosus detected by echocardiography in premature infants was 65.4 percent, especially extremely premature infants 28 weeks, birth weight 1000 grams. Clinical symptoms of patent ductus arteriosus in premature infants is rapid breathing seen in 81.7 percent, cardiac hyperactivity in 70.2 percent, strong second heart sound in 61.5 percent, rapid heart frequency in 41.3 percent and heart murmur is the least common in 10.6 percent of cases. Ultrasound result showed that 100 percent was leftright shunt. 76 percent of infants have ductus arteriosus diameter or = 2.0 mm, average size of the ductus arteriosus was 2.16 + or - 0.66 mm. Index LA/Ao, LVDd and LVDS of infants having the patent ductus arteriosus were higher than the infants having closed ductus arteriosus with p 0.05. Conclusion: Patient ductus arteriosus have very high rate in premature infant. Clinical diagnosis is often difficult because only 7 percent of cases having heart murmur. Index LA/Ao, systolic and diastolic left ventricular size of infants having the patent ductus arteriosus were higher than the infants having closed ductus arteriosus.