Hypochondriasis remains controversial, despite its 2000-year history. Although it is considered a mental disorder, hypochondriasis is often regarded as a defence mechanism, peculiar cognitive/perceptual style, means of nonverbal communication, response to stress, abnormal illness behaviour, personality trait, distinct personality disturbance, and part of other mental disorders. Disagreements about etiology and pathogenesis of hypochondriasis go hand in hand with disagreements about its treatment. This book fills the need for a modern, balanced, in-depth, and integrative overview of hypochondriasis as a mental disorder with diverse manifestations. Written by world experts and from different perspectives, it aims to be a state-of-the-art text, demonstrating how the current concepts of hypochondriasis are linked with its rich history, critically examining diagnostic and nosologic issues and suggesting ways of overcoming the conceptual obstacles, describing current views on the etiology, pathogenesis and psychopathology, presenting main treatment approaches, and providing treatment guidelines. This book is intended for both practising clinicians and researchers. An important resource for all psychiatrists, primary care physicians, clinical psychologists, and other mental health professionals, it will also be of interest for psychiatry residents, medical students, graduate students in clinical psychology, and lay public.