The purpose of this book is to provide the students, paramedical personnel and clinicians a hands on information of various diagnostic tests related to the human organ system disorders. This book is organised into four separate sections including Hematology, Microbiology, Clinical biochemistry and Immunology. This book uses the terminology that supports the scientific nature of the diagnostic process. Throughout the book the emphasis is placed on the basic underlying principles as well as the clinical correlations of various diagnostic tests. Care has been taken to confirm the accuracy of the information presented and to describe generally accepted practices.