OBJECTIVE: To present a retrospective analysis of multicentre case series of oral syphilis and a review of relevant literature. SUBJECTS AND METHODS: A PUBMED search was carried out from 1950 to 2011. Clinical records of patients with exclusive/prevalent oral manifestations of syphilis were collected and examined in three independent hospitals. RESULTS: Of 23 reports describing 34 patients were detected through the review (35% primary, 56% secondary, and 9% tertiary disease), describing unspecific ulcers (59%), mucosal patches (23%), keratosis (6%), pseudomembranes (3%), and gumma (9%). Multicentre case series revealed 12 patients with oral syphilis, of which 17%, 58%, and 25% with, respectively, primary, secondary, and tertiary lesions. Clinically, patients showed white patches (17%), blistering mucositis (8%), chronic unspecific ulcers with/without skin lesions (50%), gumma (17%), and necrosis of the dorsum of the tongue (8%). Oral bullae and tongue necrosis are never described in the current review. CONCLUSIONS: Diagnosis of syphilis remains a challenge because of the multiform and polymorphous clinical pattern at onset and its ability to imitate different diseases. It is mandatory to include syphilis in the differential diagnosis of unusual oral lesions. Diagnosis of oral lesions of syphilis is often difficult, and biopsy is required in controversial cases.