Fetal extremities were examined in 300 pregnant women between 16th and 24th week of gestation by real-time ultrasound. The limb bones of femur, humerus, tibia-fibula and radius-ulna complexes were measured and correlated to menstrual age and estimated age by ultrasound. The standard curves for limb bone growth show a linear increase with constant standard deviations. As fetal limb bone growth is close correlated to gestational age estimation of gestational age is exact as estimation from menstrual dates. Finding out skeletal malformations can be done very effective in patients of high risk.