This book comprises a collection of categorized case-based questions, directed and meticulously selected to cover the most common and most important aspects of immunodeficiency diseases. Immunodeficiency disorders of infancy and childhood such as antibody deficiencies, phagocyte defects and defects in innate immunity are addressed among others. Each chapters starts with a brief of the initial presentation and lab data of the patient, followed by a series of 5-6 multiple choice questions (MCQs), leading the reader to the diagnosis and best of practice in a step-wise manner. This MCQ format along with precise, yet detailed answer ensures a quick, case-based, reality learning to the reader. This comprehensive MCQ series, is an essential reading material that a pediatric clinician, hematologist, immunologist, transplant specialist, or pulmonologist, can not afford to miss.