Background:The presence of an immature foetal lung is linked to a variety of negative consequences, including respiratory distress syndrome. (RDS). The ability to continue or postpone birth is frequently the deciding factor efficiently assess lung maturity in the foetus. Aim of the work:To evaluate the value of assessment of amniotic fluid using ultrasonography in predicting fetal lung maturity and its impact on fetal outcome. Patients and methods: This prospective cohort study included three hundred pregnant women. They were later divided into two groups; RDS group and non-RDS group. Results: Our results indicated the presence of a significant distinction between RDS group as well as non -RDS group regarding gestational age (P value=0.0005). However, there was no statistically significant difference regarding maternal age, gravidity, parity and abortion among RDS & non-RDS fetuses (P value > 0.05). Regarding the fetal biometric measurements, our results indicated a statistically significant decrease in the values of fetal biometric measurements including BPD, FL and AC among RDS group in comparison with the non-RDS group (P value < 0.001). Conclusion: Ultrasound parameters including proximal tibial epiphysis (PTE) followed by distal femoral epiphysis (DFE) then amniotic fluid free floating particles (FFP) are precise predictors in the assessment of RDS with varying degrees of performance.