The timely recognition of fetal macrosomia may reduce the complications associated with vaginal delivery of a macrosomic fetus. Today, the most frequently used tool for identification of fetal macrosomia is ultrasound. Although many different calculations have been applied, the most commonly used is the estimation of fetal weight. Generally, the detection rate for fetal macrosomia is 33-82%, with a specificity of 70-100%, a positive predictive value of 40-83%, and negative predictive value of 66-92%. Adding amniotic fluid volume, cheek-to-cheek diameter or fetal subcutaneous tissue: femur length ratio may improve the accuracy of the diagnosis. Other promising diagnostic tools include the echo-planar imaging and the neural network. Despite the progress that has been achieved since the use of Nagele's rule, our ability to detect fetal macrosomia remains limited.