"Since the second deitoin of this book was published in 1994, knowledge of the molecular basis of blood diseases has grown exponentially. This is reflected in the contents of the trird edition of the book. Seven new chapters, on Stem Cell Biology, on Hematopoiectic Growth Factors and Rceptors, on Hematopoietic Transcriptional Factors, on Signal Transduction in the Regulation of Hematopoiesis, on Integrins in Hematology, on Paroxysmal Nocturnal Hemoglobinuria, and on Gene Therapy of Blood Diseases, have been added. All other chapters have been rewritten or extensively updated to relfect the explosion of knowledge. The first two deitions extablished The Molecular Basis of Blood Disases as a very useful resource for all individuals with an interest in hematology. We hope that the expanded and extensively updated third edition will be useful to a diverse audience, including established updated third edition will be useful to a diverse audience, including established scientists, individuals engaged in teaching and the practice of hematology, postdoctoral fellows, and residents as well as medical and graduate students."