Background: Fetal kidney length (FKL) is an accurate parameter in late pregnancy. Moreover, FKL was investigated between 24 and 38 weeks pregnant women and FKL has more accurate predictive value than the other fetal biometric parameters. This study aimed to measure the efficacy of fetal kidney length in the measurement of gestational age Methods: This cross sectional study was conducted on 120 pregnant women was recruited among cases. All patients were subjected demographic data collection, complete history taking, routine antenatal investigations, clinical examination and routine laboratory investigations: Complete blood count (CBC), liver function test, kidney function test, random blood sugar (RBS). Results: There were a statistically significant positive correlation between mean fetal kidney length and (GA LMP, BPD, BPD GA, HC, HC GA, AC, AC GA, FL and FL GA). There were statistically significant positive correlation between GA by LMP and BPD GA, HC GA, AC GA, FL GA , Predicted GA using Rt fetal kidney length, Predicted GA using Lt fetal kidney length and Predicted GA using mean length of both fetal kidneys. Conclusion: Kidneys are easy to identify and measure. Our study revealed that the mean fetal kidney length was a significant predictor for the gestational age estimation. FKL can be measured readily, and in combination with BPD, HC, AC and FL gives a better prediction of GA, especially in late second and early third trimester (beginning from 24th week – 34th weeks).