Pain is not usually considered a symptom of chronic relapsing demyelinating polyneuropathy. We report two patients with chronic demyelinating polyneuropathies in whom clinical and electrophysiological worsening was associated with the development of deep and distressing upper limb aching discomfort. One patient had a MGUS-associated hypertrophic demyelinating and prednisone-dependent polyneuropathy, followed over a course of two and a half years. His discomfort regularly predicted electrophysiological relapse of neuropathy, before more obvious clinical signs had emerged. Resolution of the discomfort also predicted subsequent clinical and electrophysiological improvement. Upper limb pain may be an important feature of early relapse in some patients with demyelinating polyneuropathies. Standardized serial electrophysiological testing in patients with chronic demyelinating polyneuropathy can be an important management tool in conjunction with clinical signs and symptoms.