Syphilis is a sexually transmitted infection by Treponema pallidum. Without antibiotic treatment syphilis lasts for several decades and may develop up to 4 different clinical stages. Usually, the disease begins with a distinct painless and indurated ulcer at the contact site: the primary chancre. An indolent regional lymph node swelling is usually associated with the syphilitic chancre. After spontaneous healing of the primary lesion and several weeks of latency, the clinical symptoms of secondary syphilis occur. Treponema pallidum bacteremia leads to common symptoms like fever and malaise, but also to a generalized lymphadenopathy, and a broad variety of lesions of the skin and mucosal membranes. Non-pruritic transient exanthems often involving palms and soles, condylomata lata, and a specific angina with mucous patches of the oral cavity are prominent signs. After several relapses, which are characterized by a decreasing intensity of clinical symptoms, secondary syphilis then resolves spontaneously. A second period of latency follows, lasting 3-12 years. Then the outcome of untreated syphilis becomes apparent: spontaneous healing by elimination/inactivation of the spirochetes (75%) or transition to tertiary syphilis (25%). Two kinds of granulomatous skin reactions are typical for tertiary syphilis: superficial nodular syphilids and gummas. The bones, as well as the cardiovascular and central nervous system, may also be involved. Finally, metasyphilis with severe and sometimes lethal neurological symptoms (tabes dorsalis, progressive paralysis) occurs 10 to 30 years after primary infection. Except for irreversible tissue destruction which occurs prior to therapy, all stages of syphilis can be cured completely.