Granulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm. This book examines the characteristics of eosinophil granulocytes, its biological functions, its role in inflammation and its clinical significance in children. This book also reviews the role of granulocytes on the onset of tissue-destructive diseases when exposed to stress. In addition to the cases of disease, some physiological phenomena are also responsible for the stress-induced granulocytosis. Thus this book will also expands upon the role of granulocytes associated with various diseases and some physiological responses. Other topics discussed in this book include the role of basophil, the minute group of granulocyte, in tropical infections and in immune regulations; polymorphonuclear neutrophilic granulocytes (neutrophils), which are the most dangerous cells in the organism and their role in transient states of autoimmunity, and the effects of nucleoli change during differentiation and maturation of granulocytes.