Abstract Background: The pulmonary system is the last fetal organ system required for extra uterine life to become functionally mature, and respiratory distress syndrome (RDS), related to pulmonary surfactant deficiency, remains a major morbidity and mortality. Aim of Study: Was to emphasize the role of fetal pulmonary artery Doppler in prediction of fetal lung maturity by compar-ing fetal pulmonary artery color Doppler results with gesta-tional age and neonatal outcome. Patients and Methods: This observational prospective cross sectional study was conducted at Ain Shams University Obstetricians & Gynecologists Hospital after approval from the hospital research ethics committee for 8 months. The study included sixty pregnant women aged 18-41 years between 28 to 40 weeks gestational age of pregnancy, had been admitted for elective cesarean, or attending the delivery unit either in active labor or indicated for selective cesarean. Ultrasound scans were performed within 48 hours for pregnant women from 28 weeks to 40 weeks. Results: Main pulmonary artery (At/Et ratio), fetal lung to liver echogenicity, free particles in amniotic fluid and placental grading were positively correlated with lung maturity. It identified main pulmonary artery At/Et ratio (cutoff >!0.30) with (92.5% sensitivity, 87.2% specificity), as reliable predic-tors of neonatal RDS. Also our study showed that gestational age, free particles of amniotic fluid, fetal lung to liver echo-genicity and placental grading were significantly correlated with development of neonatal respiratory distress syndrome as gestational age was lower on those who eventually devel-oped neonatal RDS (p-value <0.001). Furthermore, combina-tion of these measures has greater sensitivity & negative predictive value than when either measure was used alone. Therefore, these measurements might be alternatives to inva-sive procedures for assessment of fetal lung maturity before delivery. Conclusion: Main pulmonary artery (MPA) At/Et ratio, together with fetal lung to liver echogenicity, free particles in amniotic fluid and placental grading can be used as non-invasive accurate methods for prediction of neonatal respiratory distress syndrome (RDS) and fetal lung maturity (FLM), with even higher sensitivity and predictive values when in-combined. Main pulmonary artery At/Et showed significant difference between fetuses developing RDS and those who did not, but it's recommended to be combined to the other measurements, as alone it shows lower specificity along the different gestational age (GA).