Background: When a fetus's age cannot be determined from the mother's last menstrual period or an early ultrasound, the cerebellar diameter serves as a reliable predictor of GA and a standard against which other fetal measures may be evaluated. This study aims to detect an accurate method for assessment of gestational age in second and third trimester of pregnancy comparing the trans cerebellar diameter, biparietal diameter, femur length and fetal kidney length. Methods: This was an analytical study performed on 100 pregnant females in second or third trimester pregnancy attending at the Obstetrics and Gynecology Outpatient Clinic at Beni-Suef University Hospital. Fetal biometric measurements were taken using ultrasound, including TCD, BPD, FL, and fetal kidney length. Result: The TCD and KL both rise with an increase in GA and have excellent correlation coefficients, indicating good measurement agreement and reproducibility that is unaffected by the late-trimester variability Conclusion: According to the findings of this research, KL and TCD exhibit a strong correlation with fetal GA in the third trimester, while in the second trimester BPD, FL, AC and TCD are good predictors of gestational age and no role for KL at that time of pregnancy