Sexual dysfunctions in men and women cover a wide range of disorders that can affect any phase of the human sexual response. They can originate from a variety of aetiologies including (but not restricted to) neurological conditions, vascular diseases, psychological or psychiatric disorders, diabetes, lower urinary tract syndrome and prostatic conditions, all of which are covered in this book. Identifying the sexual dysfunction and its symptomatology is the first step to understanding the patients complaint, but the aetiology of the sexual disorder can also be a part of the treatment options and influence their relative effectiveness. This book is designed for a better understanding of the basics of human sexual functioning and the impact of various pathologies on the development and treatment of these dysfunctions. Following an initial definition of sexual dysfunctions in men (erectile failure, persistent erection, delayed, retrograde, premature, anhedonic or painful ejaculation) and in women (hypoactive sexual desire, sexual arousal deficit, persistent genital arousal, dyspareunia, vaginism, anorgasmia), and following a description of the normal sexual functioning in men and later in women, the book addresses the issue of contributing factors (predisposing, precipitating, maintaining factors), or etiologies, that can participate in the emergence or maintenance of sexual dysfunctions. These include neurological conditions, which also highlight the role of the brain and neural pathways in modulating sexual responses, and their impact on genital reflexes and quality of life (eg: spinal cord injury, multiple sclerosis). They include conditions such as prostatic diseases and their treatment with radical prostatectomy, or apparently benign activities such as bicycle riding (and its resulting nerve entrapment) and their impact on men's genital innervation and resulting in sexual dysfunctions. They also include general disease such as diabetes, which affects both men and women, and depression, and their resulting impact on sexual function and quality of life. Female pathologies such as womens urogynaecological disorders and aging on womens normal function are also addressed, along with a discussion of the assessments limitations and unit care concerns (eg: palliative care), which can contribute to the emergence or maintenance of sexual dysfunctions, and which are covered throughout the chapters of this book.