Paraneoplastic neurologic syndromes (PNS) constitute a rare group of disorders whose optimal treatment is yet to be established. We report a patient with bilateral orbital inflammation associated with PNS, who responded well to surgical resection of the primary tumor. An 83-year-old woman was referred to our department for treatment of a progressive reduction in visual acuity and palpebral swelling in both eyes for the past 2 months. She was scheduled to undergo thoracic surgery for lung cancer. The best-corrected visual acuity (BCVA) in the right and left eye had worsened from 0.3 to 0.5 one month before she was referred to our department to 0.03 and 0.07, respectively. A slit-lamp examination revealed edema in both eyelids. Goldmann perimetry revealed several paracentral scotomas with constriction of the peripheral visual fields of both eyes, along with central absolute scotomas in V-4e isopter in the right eye. Magnetic resonance imaging revealed swelling of the bilateral extraocular muscles, which compressed the bilateral optic nerves at the orbital apex. Seven days after the resection of the lung cancer, the BCVA improved to 0.07 and 0.15 in the right and left eyes, respectively, without concomitant immunotherapy. Intravenous methylprednisolone (500 mg/day) was administered for 3 days to treat the residual orbital inflammation. Fourteen days after surgery, the BCVA further improved to 0.4 and 0.5 in the right and left eyes, respectively. Swelling of the bilateral extraocular muscles and the visual field abnormalities improved dramatically. Early diagnosis is crucial for the management of PNS.