The wide use of penicillin and of other treponemacide antibiotics levels often to the treatment of patients with early-syphilis without knowing it. So the typical appearance of syphilis may be masked and the development of the classic serologic changes may be disturbed. From 1963 to 1974 569 cases of early-syphilis were treated as inpatients of the University clinic of Innsbruck, Department of Dermatology, 15% had proved and 20% had probable antibiotic therapy before syphilis was diagnosed. The influence on the course of disease due to treatment before noting the diagnosis is discussed by the means of own observations and reports in the literature. An attempt is made to explain the striking increase of symptomless early-syphilis.