Syphilis was first recognized as a distinct syndrome in Europe in the fifteenth century. Despite knowledge of congenital infection for more than 450 years and the existence of adequate therapy for 55 years, congenital infection remains a problem for the practicing clinician. Syphilis is caused by Treponema pallidum. Infection may be transmitted horizontally by sexual contact and vertically as a result of hematogenous dissemination across the placenta. Syphilis is classified as primary, secondary, latent, and tertiary. The diagnosis may be established by darkfield examination of clinical lesions and by serological assays. The drug of choice for syphilis is penicillin. This agent is the only antibiotic of proven value for the treatment of congenital syphilis. Accordingly, infected pregnant women who are allergic to beta-lactam antibiotics must be desensitized and then treated with penicillin.