AIM: To report a rare case of optic perineuritis secondary to syphilis infection with severe visual loss showing a dramatic improvement following treatment with corticosteroids.METHODS: Case report.RESULTS: A 66-year-old Malay lady presented to us with sudden onset of unilateral loss of vision and pain on eye movement. Her vision had no perception of light and marked relative afferent pupillary defect (RAPD) was present over the right eye. Serological and radiological investigation showed evidence of syphilitic optic perineuritis. She was treated with intramuscular benzathine penicillin and intravenous methyl prednisolone, followed by oral steroid with tapering dose for long period. Her visual acuity improved remarkably after the treatment. She regained the vision of 6/18 and there was no sign of recurrence or steroid related side effects during 4 months follow-up.CONCLUSION: Accurate diagnosis and prompt treatment of this case has converted a poor vision to a better visual outcome.