Abstract Background: Preterm premature rupture of membranes (PPROM) causes serious neonatal complications mainly respiratory distress syndrome (RDS) which affect large portion of pregnancies complicated by PPROM. Aim of Study: To compare between lamellar body count and fetal pulmonary artery Flow velocity wave forms for prediction of fetal lung maturity. Patients and Methods: This study was carried on 120 patients presented with pre-labor rupture of membranes at Al-Galaa Teaching Hospital, to compare between the roles of fetal pulmonary artery flow velocity waveforms and amniotic fluid lamellar bodies count for prediction of fetal lung maturity, in a prospective cohort study. Sonographic and amniotic fluid characteristics revealed mean amniotic fluid index (AFI) of 4.1cm with mean At/Et ratio (0.2). A mean level of lamellar body count 41683 was detected. Results: The cutoff value for LBC in predicting fetal lung maturity in our study was >!20,000/µL. Comparison between cases with RDS and cases without RDS regarding LBC level and fetal MPA Doppler indices revealed statistically significant differences on basis of LBC level (p-value 0.002), fetal MPA PI (p-value 0.003), RI (p-value 0.002) and At/Et ratio (p-value <0.001). It was noted that S/D ratio was of no signifi-cance between cases with RDS & those without RDS. Fetal MPA At/Et ratio was more sensitive and also more specific in prediction of lung maturity than lamellar body count which makes it a better choice than the invasive procedure entailing LBC measurement. Conclusion: Both main pulmonary artery (MPA) At/Et ratio and lamellar body count (LBC) be used in detecting fetal lung maturity and predicting neonatal respiratory distress but MPA AT/ET ratio are more sensitive, specific and less invasive.