BACKGROUND Pulmonary artery acceleration time (PAAT) is a reliable and non-invasive method for assessing pulmonary hemodynamics. To date, few studies have used PAAT to assess preterm infants, especially those with respiratory distress syndrome (RDS). This study aimed to assess changes in PAAT among preterm infants with RDS undergoing pulmonary surfactant (PS) therapy or not, and determine its potential effects on the pulmonary vascular disease (PVD) outcomes of preterm infants with RDS in the late postnatal period. METHODS The risk of RDS was reviewed in 62 preterm infants with a gestational age of 26-31 weeks. The infants receiving PS therapy were allocated to the PS group, and the others were allocated to the control group. PAAT, right ventricular ejection time (RVET), and other ultrasonic parameters at 3 different time points after birth were studied and compared. RESULTS Infants in the PS group had a significantly lower PAAT (52.7±5.9 vs. 59.6±8.7; P=0.001) and PAAT/RVET (0.30±0.03 vs. 0.33±0.03; P=0.001) than those in the control group at 36 weeks postmenstrual age (PMA). No significant increases in PAAT/RVET were detected at 3 different times for the PS group (P=0.117), but both PAAT and PAAT/RVET increased significantly with time after birth in the control group (P<0.001). CONCLUSIONS Preterm infants with RDS might still have PVD in the late postnatal period and thus require long-term follow-up observation. PAAT appears to be a reliable non-invasive screening measure for evaluating pulmonary hemodynamics in preterm infants with RDS and late PVD.