BACKGROUND Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy that is usually associated with preceding respiratory or gastrointestinal infection and has the hallmark manifestation of ascending flaccid paralysis. We report an atypical presentation of GBS. CASE REPORT A 76-year-old male presented with acute onset of diaphoresis and altered mental status. He subsequently developed severe bradycardia and refractory hypotension, which initially responded to dopamine infusion. A temporary pacemaker wire was placed to stabilize the heart rate but hypotension persisted. Acute autonomic dysfunction was suspected. Head and chest imaging was unrevealing. Lumbar puncture revealed albuminocytologic dissociation that was consistent with a diagnosis of GBS. Hospital course was complicated with acute kidney injury and metabolic acidosis. Plasmapharesis was initiated. The patient eventually died of multi-organ failure. CONCLUSIONS Autonomic dysfunction is a known but rare presentation of GBS. In patients presenting with refractory bradycardia and hypotension, GBS should be considered in the differential diagnosis.