The Ivemark-Syndrome (Alienie Syndrome) is defined by the characteristic association of splenic aplasia, organsymmetry and other malformations especially of the cardiovascular system. More than 200 cases are reported. The incidence of Ivemark-Syndrome is very low. The aetiology is not yet clearly defined. As a main cause exogen factors between the 31st and 38th day of gestation are discussed, but a genetic cause has not been detected yet. Due to the unfavourable prognosis an intensive ultrasonographic screening is to be asked for.