Prenatal screening of fetal aneuploidy is a continuously and rapidly evolving area of research; there have been tremendous advancements over the past decades in prenatal screening for aneuploidy, especially during the first trimester. As there is extensive evidence that effective screening for major chromosomal abnormalities can be provided in the first trimester of pregnancy, recently we have changed our practice; the prenatal screening of fetal chromosomal aberrations has been moved and pointed to the first trimester. Besides the nuchal translucency, which is one of the most known ultrasonographic markers, there are other markers, which can be examined during the first trimester of pregnancy. To maximize the quality of sonography, increase the screening sensitivity, and decrease the range of false-positive rate, all of the first-trimester ultrasound markers have well-established criteria for the measurement. With the use of high standards of scanning, the early recognition of sonographic markers of chromosomal aberrations can be helpful in forward prenatal diagnosis. On the contrary, the early diagnosis makes the termination of the pregnancy possible with fewer complications, and there is time for planning of further follow-up and interventions. How to cite this article Belics Z, Papp Z. Ultrasound Markers of Aneuploidy in the First Trimester. Donald School J Ultrasound Obstet Gynecol 2017;11(1):20-28.