In an open prospective study we analysed the effect of treatment with intravenous immunoglobulin (IvIg) in three patients with clinically pure sensory neuropathy, two of whom met the clinical, electrophysiological, pathological and cerebrospinal fluid research criteria of the American Academy of Neurology for chronic inflammatory demyelinating polyneuropathy. In all patients, subclinical signs of demyelination were present in motor nerves. Treatment with IvIg resulted in improvement of neurological functions in all three patients and in improvement of the disability score in two of them.