Main features of this book are:1. Dealing with one of the most sophisticated medical titles in an interesting format (short clinical scenarios ), to facilitate expansion of factual knowledge and to improve diagnostic and therapeutic skills of the students by simulating real clinical conditions 2. Discussing all of the main topics in the filed of fluid, electrolyte, acid and base disorders ( sodium and potassium disturbances, volume disorders, fluid therapy, ABG interpretation, metabolic acidosis and alkalosis) 3.Explaining each case by comprehensive discussions about its pathophysiological and clinical aspects 4. Using more common, real clinical scenarios which I have encountered during my clinical practice 5. Emphasizing main topics of each chapter with some important home messages and single-page diagnostic and therapeutic algorithms 6.Using schematic figures and multiple tables for better explanation of the facts 7. Giving many references for more detailed study .Regarding these issues, this book is a thoroughly updated, useful review written for all interested health care professionals.