A 64-year-old woman, with asthma and sinusal polyposis in her history, suddenly developed a painful polyneuropathy with diplopia. Nerve conduction studies, performed at the very onset of the neuropathy, could not definitely rule out a Guillain-Barré syndrome (GBS) and high-dose i.v. immunoglobulins were administered. Clinical and laboratory findings subsequently supported the diagnosis of Churg-Strauss syndrome; corticosteroid therapy was started and clinical stabilisation of neuropathy was apparently achieved. No indicators of unfavourable outcome were present at that time. Nevertheless, 30 days after the onset the patient acutely worsened with severe polyneuropathy relapse and fatal systemic diffusion to heart, kidney and mesenteric district, which a single cyclophosphamide pulse failed to control. This case highlights the possibility that a GBS-like onset of Churg-Strauss syndrome neuropathy should be regarded as a part of multiorgan, severe or even life-threatening vasculitic involvement, requiring the most aggressive treatments, regardless of the presence of recognised factors of poor outcome.