Ejection fraction measurements is an alternative to study cardiac function in the fetal left ventricle. Our aim of this study is to describe reference ranges for Ejection fraction of the left ventricle by planimetric between 17 weeks and 40 weeks in normal fetuses. 24 normal patients between 17 and 40 weeks of gestational age participated in the study. All studies will be performed using an ATL HDI 5000 and ALOKA 3500 PLUS ultrasound system. The technique is made by tracing the endothelial border of the left ventricle. The end of the diastole was assumed just after closure of the mitral valve, just prior to the onset of systole and end of the systole was the minimum cavity size visualized during the cardiac cycle. Left ventricle tracing is better because the right ventricle has the moderator band doing most of the time very difficult to know where is the real cavity. All data's were analyzed in computer statistical program (Stata software). The Ejection Fraction of the left ventricle (EF%LV) at 10 to 20 weeks is 63%. Low value is 54%. Maximum range is 74%. Standard deviation is 7.230886. (EF%LV) at 21 to 30 is 59.23%. Low value 48%. Maximum range in 72%. Standard deviation is 7.639305. (EF%LV) at 31 to 40 weeks is 59.5%. Low value 50%. Maximum range is 69%. Standard deviation is 13.43503. The median (EF%LV) value is 59.45833% for fetuses between 10 to 40 weeks. We don't find significant differences in values of the left ventricle ejection fraction between the groups (p=0.56) Left ventricle ejection fraction measurements by planimetric doesn't change with the gestational age. Ejection fraction is not correlated with the left ventricle size.