Chronic inflammatory demyelinating polyneuropathy (CIDP) is a defined clinical entity with a chronic progressive or chronic relapsing course, lasting months to years. It causes variable but often severe chronic disability. CIDP is considered an autoimmune disorder caused by both cellular and humoral immune processes. Various immunomodulatory therapies, i.e., Mg, therapeutic plasma exchange (PE), and prednisone, are of proven benefit. Comparative studies indicate that Mg and PE confer equal short-term benefit. Efficacy of Mg is maintained; regularly timed pulse treatments may stabilize relapsing CIDP. The combination of Mg and prednisone may be advantageous in long-term management. Despite the high cost, Mg is considered the preferred first treatment. The safety profile is similar to that reported far other conditions; close monitoring during the infusion is recommended. The precise mechanisms of Mg action in CIDP are not known. Anti-idiotypic neutralization of autoantibodies, binding of complement, and blockade of macrophages may prevent the ongoing inflammatory demyelination.