The Authors report three cases of ophthalmic neurosyphilis in patients who complained a visual decrease monocular. The diagnosis was performed with physical and fundus examination, electrophysiological, hemato-chemical and microbiological tests, fluorangiografy and RMN. The physical examination provided standard results about eyes interested while the fundus examination, as well as the electrofunctional and fuorangiografy examinations, showed some alterations. The sockets and encephalon RMN were normal. Moreover; the patients were submitted to specific haematic and microbiological laboratory tests which showed positivity for syphilis. To sum up all patients received an incidental diagnosis of syphilis. This trend could be attributable to an extensive use of antibiotics that changing the natural course of disease, mask clinical evidences and make them harder to diagnose.