Background: IgG4 autoantibodies to neurofascin-155 (NF-155) have been described in a subset of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). While reports suggest an acute onset is more likely than in antibody negative CIDP, little literature exists around the subsequent course of NF-155 positive cases that originally presented with an acute inflammatory demyelinating polyneuropathy (AIDP) phenotype. Methods: Two male patients, ages 51 and 59, presented with similar, <2 week histories of lower extremity weakness. Patients were diagnosed with AIDP and treated with IVIG. Following initial improvement, both patients relapsed. One patient was treated with IVIG and steroids with subsequent improvement; however, he was unable to be weaned from steroids without experiencing recurrence of symptoms. The other patient was not retreated. Testing for NF-155 IgG was sent. Results: The first patient ultimately required Rituximab for stable improvement, the other improved spontaneously. Both patients later had positive tests for NF-155 IgG4 antibodies. Conclusions: Both of our NF-155 positive cases had initial AIDP-like presentations, followed by a relapsing course and excellent eventual recovery. This result, along with limited other available cases, suggest that in patients with an AIDP-like presentation, NF-155 IgG4 autoantibodies could be a marker of disease recurrence, but do not necessarily predict a poor outcome.