Loeys-Dietz syndrome( LDS) is a recently recognized autosomal dominant connective tissue disorder. Mutations in the genes encoding transforming growth factor-beta( TGF-β) receptor 1 and (2 TGFBR1, TGFBR2)have been associated with LDS. We report here 2 cases of LDS in childhood. Case 1 was a 10-year-old man, who had aneurysm of both the pulmonary trunk and the ascending aorta, associated with pulmonary and aortic valve insufficiency. Surgical repair was performed successfully at the age of 17. The aortic valve was replaced with a mechanical valve. The aneurysmal ascending aorta was replaced with a Dacron graft. Pulmonary valvuloplasty and pulmonary arterioplasty was performed. Case 2 was a 3-month-old female infant, who had a patent ductus arteriosus( PDA) and aortic root dilation. A detailed physical examination revealed hypertelorism, bifid uvula, retrognathia, talipes equinovarus, and camptodactyly. Computed tomography and echocardiography demonstrated PDA, Valsalva sinus dilation, and arterial tortuosity. These findings were consistent with the clinical manifestations of LDS. Surgical ligation and clipping of the PDA was performed with good results. A molecular genetic analysis subsequently demonstrated a heterozygous missense mutation of the TGFBR2. Since aortic dissection occurs at smaller aortic diameters, early diagnosis and close monitoring are important for patients with LDS.