Five patients infected with immunodeficiency virus who were suffering from chronic polyradiculoneuropathy were investigated during evolution of the disease. Four of them were immunodeficient. The prominent neurological feature was distal and symmetrical weakness of the legs. After 5 months only one patient had improved. All patients had an increased protein level in the cerebrospinal fluid and pleocytosis. Electrodiagnostic studies and sural nerve biopsies indicated demyelination. Sural nerve viral cultures, including human immunodeficiency virus, were negative. The presence of circulating anti-peripheral nerve antibodies and of immunoglobulin deposits in nerve biopsy specimens was investigated by immunofluorescence techniques but failed to demonstrate any immunoreactivity.