Previous studies show few cases of concomitant Guillain-Barré syndrome (GBS) and acute transverse myelitis (ATM), also described as GBS and ATM overlap syndrome. We experienced a patient who presented with acute progressive leg weakness and hyperreflexia at initial stage, but was followed by areflexia. The spine magnetic resonance imaging revealed radiological findings of ATM and nerve conduction studies showed electrodiagnostic findings of acute motor axonal neuropathy, known as GBS subtype. The response to treatment with intravenous immune globulin was good.