This text is tailored to be simple, easily understandable to meet the needs of medical laboratory students on both the two and four year levels of Bachelor of Medical Laboratory. Immunology is newly science and even-changeable field, so I tried to simplify and summarize the basic and the clinical immunology. The aims of this book: to understanding the most important principles governing the basic immunology, clinical immunology and function of the immune system, to serve as a valuable reference about new developments in the field of immunology for medical laboratory students and other health professionals, to provide the necessary balance of theory with practical application because it is essential for the practitioner to have a thorough understanding of the theoretic basis for testing methodologies and finally, this book focused on immune responses against infectious microbes.