During recent years chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) has been characterized on the basis of clinical and laboratory findings. Immune modifying treatment with glucocorticoids, plasma exchange and infusion of immune globulins has had a therapeutic effect in controlled studies. Decisive for increased therapeutic efforts against CIDP in Denmark is intensified electrophysiological search in patients with polyneuropathy with examination of several nerve segments for evidence of demyelination including conduction block, potential dispersion and reduction of conduction velocity by more than 40%.