Abstract Mechanisms in Hematology is a book with an accompanying interactive CD-ROM designed to assemble basic concepts that underlie clinical understanding and progress. It is presented as a concise text with a series of diagrams that distill diffuse information into a compact form. The interactive CD, in particular, brings many of the processes “to life” as details of the more complex pathways are conveyed in clear visual images. The text begins with the basic molecular biology that underlies hematological and oncological physiology/pathology––cell signaling, adhesion molecules and apoptosis. This is followed by sections, among others, on hematopoiesis, iron, B12 and folate metabolism, neutrophil function, immunoproteins, chemotherapy and coagulation. With the permission of the authors and publisher, The Oncologist has reproduced the section on lymphocytes, which we think our readers will enjoy.