We report a case of a 61-year-old man with a history of squamous cell carcinoma of the lung presenting with rapidly progressive symmetric ascending weakness with areflexia. The weakness was quickly followed by respiratory decompensation requiring intubation. Lumbar puncture yielded cerebrospinal fluid with elevated protein (177 mg/dL), normal glucose (61 mg/dL), normal red blood cell count (0 per/µl), and normal white blood cell count (0 per/µL). Emergent magnetic resonance imaging of cervical, thoracic, and lumbar spine did not show evidence of metastatic disease, fracture, subluxation, or other causes of cord compression. The patient was diagnosed with acute inflammatory polyneuropathy, also known as Guillain-Barré syndrome. Despite treatment with a five-day course of intravenous immunoglobulin and a subsequent five-day course of plasmapheresis, the patient did not recover respiratory function and died 48 days after diagnosis. To our knowledge, this is the first documented case of Guillain-Barré occurring concomitantly with squamous cell carcinoma of the lung.