Background; in obstetric care, knowing the exact age of the foetus is crucial. Uncertain dates and no allocated ultrasound date in the first trimester create a management issue, resulting in iatrogenic pre or post maturities. Aim of work; to correlate the length of fetal kidney in normal singleton pregnancies in late second and early third trimesters (24:34 weeks) with gestational age GA derived from the first day of patient known last menstrual period (LMP) and compare it with gestational age (GA) derived from femur length. Subjects & methods; This prospective observation study was conducted on 330 pregnant women in late 2nd and early 3rd trimesters from 24 – 34 weeks in Obstetrical and Gynecological department Benha University hospitals “inpatient wards and outpatient clinics” and were assessed by two-dimensional ultrasound. Result; mean ± SD of gestational age was 29 ± 3 weeks (range, 24 to 34 weeks). The mean ± SD femur length was 67.5 ± 6 mm (range, 54 to 79 mm). The mean ± SD right kidney length, left kidney length and average kidney length was 33.5 ± 3 mm (range, 27 to 40), 34 ± 3 mm (range, 27.4 to 40.6 mm) or 33.5 ± 3 mm (range, 27 to 40.5 mm), respectively. Mean fetal kidney length (R2= 0.92) is more accurate than femur length (R2 = 0.87) in estimation of gestational age in third trimester. The difference between both right and left kidney length was statistically significant but was too small to be of clinical value (0.5 mm), the left kidney length was higher than the right kidney length. Conclusion; FKL is a potentially useful parameter during ultrasound and antenatal checkups, especially in late second and early third trimester (beginning from 24th week – 34th weeks). FKL accurately predicted the EDD.