Onychoptosis is the periodic shedding and falling of one or more nails, in whole or part. It can be seen after fever, trauma, adverse reaction to medications, and in systemic illnesses including syphilis (syphilitic onychia). We report a case of 38-year-old man presented with subacute bilateral retrobulbar optic neuritis. Physical examination revealed diffuse onychoptosis which lead into the diagnosis of neurosyphilis. Symptoms significantly improved with appropriate treatment with intravenous penicillin G for 14 days.