Congenital syphilis has been diagnosed very seldom in ancient populations. The case that we examined comes from San Jeronimo's Church (17th and 18th centuries AD; Mexico City). Coffin 43 contained an incomplete skeleton of an approximately 2-year-old infant. The pathological lesions of this skeleton include bilateral osteochondritis, diaphyseal osteomyelitis, and osteitis and/or periostitis on the long bones. The radiographic appearance depicts symmetrical osteomyelitic foci, particularly at the proximal extremity of both tibiae (Wimberger's sign). The skull exhibits hydroceph-aly and periosteal changes on the vault, and the unerupted upper incisors evince dental hypoplasia and other pathological alterations reminiscent of Hutchinson's incisors. All these features strongly suggest a case of early Congenital syphilis. © 1995 Wiley-Liss, Inc.