PURPOSE: To describe a case of ehrlichiosis optic neuritis. DESIGN: Single observational case report. METHODS: A 41-year-old woman with symptoms and clinical and imaging signs consistent with optic neuritis presented to a tertiary care academic center for comprehensive neuro-ophthalmic evaluation. Main outcome measures included preoptic and postoptic neuritis polyvalent ehrlichiosis titers and magnetic resonance imaging (MRI) of orbits with gadolinium. RESULTS: Ehrlichiosis titers drawn 11 days before onset of eye symptoms were negative. Titers drawn 7 days after symptoms began were positive. The optic nerve enhanced with gadolinium on MRI. CONCLUSIONS: Ehrlichiosis can cause optic neuritis and should be considered in patients with optic neuritis after a febrile, flu-like illness in an endemic area.