This volume represents the fifth edition of Hematology: Basic Principles and Practice. The initial concept for this textbook was formulated over two decades ago, and each edition of the book has evolved in response to the dramatic advances that have occurred in hematology. This evolution is a testimony to the continued energy of the editors, contributors, and readers of the book. The editorial board has incorporated scientific and diagnostic and therapeutic advances in hematology into each edition so that that the practicing hematologist, laboratory researcher, clinical researcher, student, or healthcare professional might more easily keep pace with this field and more effectively practice their craft. This text is intended to make modern hematology an exciting discipline that can be easily accessed by its diverse readership.