Fetal/neonatal immune thrombocytopenias result from increased platelet destruction by maternal antiplatelet antibodies. There is a risk of intracerebral haemorrhage and therefore of neurological impairment or death during the thrombocytopenic period, especially if a defective platelet function co-exists. As no maternal parameter is predictive of the fetal platelet count, the only reliable assessment of the fetal status depends on the fetal blood sampling. Only in case of materno-fetal alloimmunisation the therapy initiated to reverse fetal thrombocytopenia was shown to be effective, but the optimal mode of antenatal treatment is currently under study. As the neonatal therapy and the management of subsequent pregnancies are somehow different it is mandatory to make the distinction between the auto or allo-origin of the fetal thrombocytopenia. The definition of high risk pregnancies will be of help for the development of a routine screening program.