The oral cavity is the most common extragenital site of infection. We report a case of a 50-year-old female with isolated oral ulceration as the presenting manifestation of secondary syphilis. In contrast with the oral lesions of primary syphilis, which tend to be solitary, painless, indurated ulcers, oral lesions of secondary syphilis are typically painful, multiple, and accompanied by a concomitant cutaneous eruption.