Plasmapheresis was used in the treatment of a 55-year-old man with serious Guillain-Barré polyneuropathy increasing in intensity despite treatment with steroids and azathioprine. The treatment was started in view of reports in the world literature suggesting that the method is effective in autoimmune diseases. A very good effect was obtained, the patient who had had quadriplegia and respiratory failure began to move about unaided. No complications were observed during this treatment. In severe Guillain-Barré syndrome plasmapheresis should be used after exhaustion of other therapeutic methods since it gives a probability of improvement.