A considerable proportion of aortic aneurysms are shown to have genetic backgrounds. The COL3A1 gene, which encodes type III procollagen and causes Ehlers-Danlos syndrome (EDS) type IV, is one of the candidate genes associated with aortic aneurysms. The COL3A1 gene is also associated with cervical artery dissections (CAD) mostly as a part of manifestations of EDS type IV. We describe a 34-year-old Korean woman with both abdominal dissected aortic aneurysm and CAD accompanying atrial septal defect and multiple cysts in ovary and thyroid glands. She lacked cardinal manifestations of EDS type IV other than the vascular abnormalities, but molecular analyses of the COL3A1 gene confirmed a de novo heterozygous missense mutation that has not been reported before (c. 781G > A; Gly261Ser). This case suggested that the COL3A1 gene could be one of etiologically linked genes in isolated vasculopathies such as aortic dissected aneurysm or CAD, although being rare.