Cardiovascular anomalies are found in 50% of the cases of Turner's and Noonan's syndromes-diseases with the same phenotype but with a different genotype. In the former, the most common congenital heart diseases are aortic coarctation (30%) and bicuspid aortic valve (34%), while in the latter they are pulmonary valvular stenosis (60%), interatrial septal defect (25%) and obstructive or non obstructive hypertrophic cardiomyopathy (17%). We have described two cases, respectively of Noonan's and Turner's syndrome. The prominent features of the first case are the transmission of the syndrome on the male line, since father and son--the latter being our patient--are affected with the same syndrome, and the occurrence of a non obstructive hypertrophic cardiomyopathy involving both the ventricles, a situation not yet described in Noonan's syndrome. A subvalvular membranous aortic stenosis has instead been found in our patient with Turner's syndrome: this cardiac anomaly has never been described within the aforementioned syndrome in medical literature.