The occurrence of brachial plexus neuritis during the acute phase of vasculitis is uncommon. We describe a patient with a long history of rhinitis and a recent onset of asthma, who developed purpuric skin lesions, abdominal pain, eosinophilia and brachial neuritis along with evidence of sacral plexus neuropathy. High dose steroids and cyclophosphamide induced a remission. He stopped all medications after 3 years and after 6 years the patient has some fixed minimal residual neurological deficit. The importance of aggressive therapy in treating extensive polyneuropathy during the acute phase of hypersensitivity vasculitis is raised. A possible cytotoxic role of eosinophils in the pathological process is suggested.