We report a black female with past history of sexual promiscuity who developed arthroosteitis of clavicula and sternoclavicular joint and cranial osteitis during secondary syphilis. Spirochaeta were identified in the material from osteoarticular biopsy. The patient was treated with benzathine penicillin, 2,400,000 U weekly for three weeks. There was a complete clinical recovery. We emphasize the uncommon occurrence of osteoarticular involvement in secondary syphilis and the exceptional character, according to the literature, of the finding of spirochaeta in the biopsy material. We discuss the differential diagnosis and we review the literature on secondary syphilis. We suggest that syphilis should be considered in the differential diagnosis of any acute arthritis or osteitis, particularly when the involved joint is the sternoclavicular and the patient is sexually promiscuous.