Turner's syndrome is associated with congenital heart disease in a third of cases. Several reports of aortic dilatation and of death by dissection or rupture of the aorta have been published. The authors undertook a prospective study to assess the incidence of cardiac malformations and aortic dilatation in genetically confirmed Turner's syndrome. Twenty-six out of 34 patients recalled (76%), aged 7 to 30 years (average 17 +/- 6 years) accepted their inclusion in this study and underwent clinical examination, ECG, chest X-ray and echocardiography. Thirteen patients had a monosomy 45X and 13 a mosaic or structural abnormality. Six had a history of cardiovascular disease (operated coarctation: 2 cases, kinking: 2 cases, Hypertension: 2 cases). Eight patients (30%) had one or several anatomical cardiovascular abnormalities: bicuspid aortic valve (19.2%), abnormalities of the aortic isthmus (kinking or coarctation) (15.4%), aortic regurgitation (7.7%), mitral stenosis (3.8%), partial anomalous venous drainage (3.8%), patent ductus arteriosus (3.8%) and left superior vena cava (11.5%). Systematic evaluation of the aorta resulted in the diagnosis of dilatation of the ascending aorta in 1 case and dilatation of the sinus of Valsalva in 2 other cases. The authors conclude that echocardiographic evaluation is essential after the diagnosis of Turner's syndrome. It should be repeated regularly to detect dilatation of the aorta which carries the risk of serious complications, such as rupture or dissection of the aorta.