Background: the accurate knowledge of gestational age is a keystone in an obstetrician's ability to successfully manage the antepartum care of a patient and is of critical importance in ante-natal test and successful planning of appropriate therapy or intervention. Failure can result in iatrogenic prematurity which is associated with increased perinatal morbidity and mortality. Objectives: the aim of this study is to evaluate the accuracy of fetal kidney length in estimation of gestational age in normal singleton pregnancies. Patients and Methods: observational study, the study was conducted at the antenatal outpatient clinics of Obstetrics and Gynecology at Alzahraa University hospitals and Ahmed Maher Teaching hospital in the period between December 2017 and December 2018. Approval from Ethical Committee at Al Zahraa University was taken. This study included 120 asymptomatic, pregnant women, with singleton pregnancy (30 cases at each gestational age 32, 34, 36 & 38 weeks gestation). Results: the study shows that fetal kidney length is a good indicator of gestational age and can be used alone due to its accuracy in comparison to other measurements (BPD, FL &AC) that may be changed in the third trimester. There was a significant difference between right and left kidney length through different age of gestation (The Lt KL measurement was larger than the measurement Rt KL). Gestational age in weeks is nearly equal to MKL. Conclusion: fetal kidney length correlates well with gestational age, so it can be concluded that kidney dimensions can be helpful in determining the gestational age when menstrual dates are uncertain.