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Rituximab in treatment-resistant CIDP with antibodies against paranodal proteins Objective: To describe the response to rituximab in patients with treatment-resistant chronic inflammatory demyelinating polyneuropathy (CIDP) with antibodies against paranodal proteins and correlate the response with autoantibody titers. Methods: Patients with CIDP and IgG4 anti–contactin-1 (CNTN1) or anti–neurofascin-155 (NF155) antibodies who were resistant to IV immunoglobulin and corticosteroids were treated with rituximab and followed prospectively. Immunocytochemistry was used to detect anti-CNTN1 and anti-NF155 antibodies and ELISA with human recombinant CNTN1 and NF155 proteins was used to determine antibody titers. Results: Two patients had a marked improvement; another patient improved slightly after 10 years of stable, severe disease; and the fourth patient had an ischemic stroke unrelated to treat-ment and was lost to follow-up. Autoantibodies decreased in all patients after rituximab treatment. Conclusions: Rituximab treatment is an option for patients with CIDP with IgG4 anti-CNTN1/ NF155 antibodies who are resistant to conventional therapies. Classification of evidence: This study provides Class IV evidence that rituximab is effective for pa-tients with treatment-resistant CIDP with IgG4 anti-CNTN1 or anti-NF155 antibodies. Neuro