Because of the rapid development of sonography, there are many new informations on embryonal and fetal circulation and pathophysiology of decompensation. Echocardiography is a useful tool to follow intrauterine therapy. Authors have examined the effect of prenatal diagnosis on the prevalence of heart abnormalities, terms of cardiac surgery, perinatal mortality and mortality due to heart abnormalities or decompensation. During five years they have found 187 severe heart abnormalities. Because of parental request 90 pregnancies have been terminated. Following prenatal diagnosis in 16 cases planned surgery of the newborn, in 14 cases planned cesarean sections have been done. From 64 transplacentar treatments 44 patients have survived. Authors have found, that prenatal diagnosis had good effect on short term survival rate but had no effect on long term survival rate. Fetal echocardiography has selective and therapeutic effect. The selective effect depends on second trimester screening. The therapeutic effect was significant in cases of arrhythmias and decompensation.