The history, neurophysiology, clinical aspects and treatment of pruritus are reviewed in this article. The different forms of pruritus in dermatological and systemic diseases are described, and the various aetiologies and pathophysiology of pruritus in systemic diseases are discussed. Lack of understanding of the neurophysiology and pathophysiology of pruritus has hampered the development of adequate therapies. Nevertheless, the discovery of primary afferent neurons and, presumably, second-order neurons with typical histamine responses mediating pruritic sensations can be regarded as a breakthrough in our understanding of the mechanisms behind pruritus. The number of experimental and therapeutic studies has greatly increased during the past few years, reflecting an increased interest in this topic. However, further effort is needed to develop new therapeutic concepts and clarify some confusion arising from promising case reports and uncontrolled clinical studies. A precise work-up for evaluating patients with pruritus is proposed, which may help the physician to identify the underlying causes and thus to treat the patient appropriately.