The diagnosis of congenital heart disease by means of echocardiography is already a real fact. The use of this technique for diagnosis in utero currently allows the detection of these malformations during the early stages of pregnancy and to determine the prognosis of the fetal cardiopathies, as well as to establish a medical or surgical treatment of the neonate. The prenatal echocardiographic study of 126 pregnant women, previously having had children with heart disease, has allowed s to prove the greater incidence of cardiopathy in this population (6.4%), compared to the results obtained from a group of pregnant women previously having normal children and without a high risk pregnancy (0.8%). These findings support the theory that genetic factors are the primary cause of congenital cardiac malformations, although the existence of teratogen factors (rubella, diabetes, etc.) in some cases cannot be excluded.