Recently so-called micropore blood transfusion filters have been introduced. They should decrease the number of microemboli produced by blood transfusion and thus decrease the incidence of postoperative and posttraumatic pulmonary insufficiency. Since these filters are rather expensive and several types and models are offered, it seemed to us important to review their properties and the results obtained with the most commonly used models (Pall, fenwal, Swank and Bentley). The efficacy of the various filters is apparently quite different. Depending on the indication, the use of different filters is possible. There is no filter which fulfils all prerequisites which must be made for an ideal micropore filter. On the basis of our literature review we conclude that filters made of Dacron wool are best suited for all purposes. There are no good reasons to use these micropore filters routinely for all blood transfusions. However, when large amounts of blood must be given rapidly and pulmonary function is already reduced, the use of micropore filters routinely for all blood transfusions. However, when large amounts of blood must be given rapidly and pulmonary function is already reduced, the use of micropore filters seems reasonable.