Demyelinating polyneuropathy with anti-myelin associated glycoprotein (anti-MAG) antibodies is an immune mediated disorder characterized by proximal and distal symmetric weakness. Electrophysiological measurements depict features characteristic for demyelination, including prolonged distal latency, retarded conduction velocity, delayed or absent F-waves, and, rarely, partial conduction block. We report on a 65-year-old patient who was diagnosed with demyelinating polyneuropathy and anti-MAG antibodies five years before admission. Despite immunosuppressive agents and extracorporeal therapy (plasmapheresis) the disease progressed as assessed by clinical symptoms and neurological tests. Laboratory results showed an increase of serum immunoglobulin M and anti-MAG antibodies over time. Because of progressive disease we decided to treat the patient with immunoadsorption followed by application of the anti-CD20 antibody, rituximab. Six cycles of selective immunoadsorption were performed over three-weekly intervals with a repetitively used column (Globaffin); each cycle consisted of four consecutive daily treatments. Starting at cycle 4 the anti-CD20 antibody rituximab was administered with 375 mg/m(2) after immunoadsorption. The pretreatment anti-MAG antibody level of 10,000 U/mL, indicating disease activity, initially increased during treatment to a maximum of 30,559 U/mL. However, after completion of the six cycles, the anti-MAG level had decreased to 2348 U/mL; 16 months after the last immunoadsorption cycle the anti-MAG level had increased to 4134 U/mL, while the conduction velocity and compound motor action potentials remained stabile. Immunoadsorption in combination with a monoclonal anti-CD20 antibody in patients with demyelinating polyneuropathy with anti-MAG is effective and can be used an alternative treatment option in patients with progressive disease.