The concept of leukocyte depletion has been acknowledged as a mandatory procedure in transfusion medicine for a while. Within recent years, leukocyte removal filters have also become a more and more important tool in cardiac surgery, where this procedure is a logical strategy to limit neutrophil-mediated disorders. The complex biology of neutrophils therefore represents a major point of interest of this volume. Different clinical settings and the corresponding leukocyte filtration methods are a further topic of discussion, including transfusion, transplantation, perfusion and filtration modalities, blood cardioplegia as well as future filtration strategies such as bioactive cytokine filters. Aiming to provide an overview of the experience with experimental and clinical leukocyte filtration and of the state-of-the-art in clinical application, this book also gives an outlook on the possible future role of leukocyte depletion in cardiac surgery and cardiology.