Demyelinating inflammatory diseases of central and peripheral myelin share similar aetiopathogenesis but rarely occur simultaneously in the same individual. Here we report two clinical cases of temporal association between multiple sclerosis (MS) and chronic inflammatory demyelinating polyneuropathy (CIDP). Our finding supports the hypothesis that clinically manifested central and peripheral demyelinating diseases could result from a common pathogenic event characterised by T-cell autoimmunity spreading from central to peripheral myelin.