Objective: estimation of accurate gestational age correctly remains a crucial step in the antenatal care provided to all pregnant women. Our aim was to find out if transcerebellar diameter (TCD) could aid precisely in detecting accurate gestational age using ultrasound. Patients and methods: One hundred and three healthy women with singleton pregnancy were included. Pregnancies complicated with fetal anomalies, intrauterine growth restriction or death were exclud- ed. Eligible participants were examined extensively by ultrasound to confirm the gestational age using TCD, biparietal diameter (BPD) and femur length (FL). Then, data were collected and statistically analyzed comparing the three measurements. Results: TCD was accurate within in 88.3% of the cases, while FL was accurate in 65% of the cases and BPD was accurate 51.5%. Bland-Altman comparison of actual GA and GA estimated by TCD, FL and BPD showed narrow limits of agreement indicated low bias and better test with TCD, thus GA estimated by TCD was the best .There was good correlation between actual GA and GA estimated by TCD (r=0.989**, p < 0.001). Conclusion: TCD is the highest statistically significant measure- ment which could be used in the third trimester for assessing the ges- tational age compared with FL and BPD without any effect of parity, gestational age or fetal presentation on its accuracy.