Since its initial description in 1851, Munchausen syndrome has been widely used interchangeably with factitious disorder. Nevertheless, this syndrome is only one form of factitious disorder that is both severe and chronic. The syndrome was named after Karl Friedrich Hieronymus, Baron von Münchhausen (1720-1797), a German nobleman who became famous as a narrator of false and exaggerated exploits. His name was progressively corrupted to Munchausen. Factitious disorders and Munchausen syndrome remain a great diagnosis challenge for physicians. All medical specialities are concerned by these disorders. The diagnosis process involves a first step to exclude an unusual presentation of a common medical condition. The second step consists of excluding somatoform disorders and malingering. Unfortunately, the boundaries between factitious disorder, somatization, and malingering are often unclear. In 1977, the term "Munchausen's syndrome by proxy" was coined to define a situation where a person produces false symptoms in another one, especially a child. This term was extended to similar interactions between human and pets. Because varied conditions have been included in the definition of this syndrome, there is ongoing debate about alternative names.