Hemodilution therapy in acute cerebral infarction is still a controversial issue. This is mainly due to the different results achieved in clinical studies so far. Criticism, however, is justified in some points. The reason for the different results of the studies is very likely to be the selection of the patients, i.e. the poor differentiation of acute cerebral infarctions. In addition, the different therapy regimens applied must be taken into account. Thus, several questions arise in connection with the clinical application and the further investigation of this therapy which have so far been answered not at all or only in part. Since there is at present no appropriate alternative treatment for acute cerebral infarction, hemodilution is most likely to remain an important therapy in this indication.