This book provides a comprehensive overview of dual disorders from a clinical and therapeutic point of view, especially for patients with heroin use disorder. The volume opens with a first part dedicated to the guiding principles for treating dual disorder patients in which terminology, treatment models, use of opioid medications in heroin addiction and future perspectives are reviewed. A second part is devoted to mood disorders. Anxiety disorders that might affect these patients are discussed in the third part, whereas the fourth part of the book focuses on chronic psychotic patients with heroin use disorder. The conclusive part explores violent heroin-dependent patients with alcohol use disorder and polydrug use. The book will be a valuable tool for psychiatrists who wish to broaden their knowledge about addictions and a key resource for other clinicians who have practical knowledge of the addictive phenomena but are not familiar with their description inneurobiological or psychopathological terms.