The accurate diagnosis of fetal malformations in utero can provide both heath care providers and parents a number of management options. Three-dimensional ultrasonography is a new technique of diagnosis which has several potential advantages to allow for evaluation of specific anomalies by permitting highquality views of body surface. We report 4 cases of fetal chromosomal abnormalities including 2 cases of trisomy 21, 1 case of trisomy 13 and 1 case of 48, XXY/+18. All cases were proved to have abnormal chromosomes by amniocentesis or percutaneous umbilical cord blood sampling. After 3D reconstruction, we can identify specific facial abnormalities which can not be visualized by conventional two-dimensional
ultrasound such as low set ear, Mongolian’s slant eyes, facial dysmorphism of trisomy 13 and trisomy 18. We also clearly visualized abnormalities of digits such as overlapping fingers, club hands and sandal gap. Three-dimensional reconstruction of the fetal body surface improves the antenatal diagnosis of chromosomal abnormalities characterized by a particular dysmorphism. Our report suggests that three-dimensional
ultrasonography has the potential to provide novel informations on the fetal anatomy and be useful in visualization and identification of chromosomal abnormalities in utero.

Keywords: Three-dimensional Ultrasonography, Chromosome Abnormalities, Trisomy 21, Trisomy 13, Chromosome 48, XXY/+18