Trisomy 3q is a very rarely reported chromosomal disorder. Duplication of part of the long arm of human chromosome 3 causes a distinct and severe syndrome that leads to multiple congenital abnormalities. A 27 year-old pregnant woman was admitted to our clinic at 17 weeks of gestation. Prenatal sonography identified a fetus with an omphalocele that contained the liver and bowel, mild ventriculomegaly and polyhydramnios. Amniocentesis revealed the karyotype of 46, XY, der (3) (3qter→3q21:: 3pter→3qter). The pregnancy was subsequently terminated. Postnatally, the proband showed midfacial hypoplasia, micrognathia, hypoplastic 12th ribs, omphalocele and prominent heels. We reported this partial trisomy 3q case because he had less marked malformations compared to other reported cases and also different features such as an omphalocele and hypoplastic 12th rib which have not been described previously in an isolated Trisomy 3q case with this karyotype.