Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract that is frequently accompanied by systemic complications. Neuropathologies have not been well investigated as extraintestinal manifestations of CD. We herein report the case of a 36-year-old man with CD who presented with progressive weakness and numbness. A neurological examination and the results of a nerve conduction study and a sural nerve biopsy led to a diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Plasma exchanges were initially effective; however, the effects gradually declined starting 10 days after the plasma exchange (PE). These results suggest that humoral factors may play an important role in CIDP associated with CD.