The objective of this review article is to inform about the role of the ultrasonographic appearance of the fetal nasal bone in the prenatal screening for the diagnosis of the Down syndrome. During the pregnancy the identification of affected fetuses is dependent on sonographic markers, such as nuchal translucency, nuchal fold, pyelectasis, hyperechoic bowel, echogenic intracardiac foci. Today the appearance of the fetal nasal bone can be used as a new promising ultrasonographic marker for the Down syndrome during the pregnancy. Normally the fetal nasal bone is sonographically apparent at 11 weeks of gestation and the fetal nasal bone length increases with the increase of the crown-rump rump length of the fetus. The absence or the hypoplasia of a nasal bone is associated with a high risk for trisomy 21 and it is a highly sensitive and specific marker for this chromosomal abnormality. Recently the nasal bone has been shown to be absent in the majority of the fetuses with Down syndrome, compared with a small percentage of normal fetuses. Therefore a short or an absent nasal bone is associated with an increased likelihood ratio for fetal Down syndrome. The addition of the fetal nasal bone in the prenatal screening for the detection of the Down syndrome can increase the detection rate and decrease the false positive rate.