To compare between regular last menstrual period (LMP) and ultrasonography crown–rump length (CRL) measurements in predicting the delivery dates (EDD) in a Syrian population. This was a prospective observational study of women with a normal spontaneously conceived viable singleton pregnancy, a regular menstrual cycles, and spontaneous onset of labor at term. The LMP was considered certain in all cases. We used ultrasound to scan 101 fetuses (72 Healthy women) at 66-12 6 weeks. The CRL of each fetus was measured three times, the mean of which was used to derive the best-fit regression model for estimation of gestational age in relation to CRL. The duration of pregnancy from the scan to the day of spontaneous delivery was predicted by CRL using regression model. The accuracy of each method in predicting the day of delivery was determined by Paired–Samples T-TEST. The true delivery dates were compared with estimates based on LMP and CRL. The results were represented as tables & diagrams. The LMP gave later estimates, while CRL gave earlier estimates from true Delivery dates. in spite of the is significant difference (P< 0.001) between CRL measurements and LMP in predicting the delivery date, but these were small clinically, and CRL was more accurate. This is of clinical importance, especially in women who forget the exact LMP, and therefore we can rely on CRL measurements.