In multifocal motor or sensorimotor neuropathy with persistent conduction block, most of the recent research has concerned treatment. Open trials show that intravenous immunoglobulin is effective, providing a rapid and often marked clinical improvement, accompanied by a significant reduction of conduction block in some cases, but without any significant change in the titre of anti-ganglioside GM1 antibodies. However, long-term therapy with intravenous immunoglobulin seems to bring less improvement than expected, and further trials are needed to study the efficacy of other immunosuppressive drugs, such as oral or intravenous cyclophosphamide. These treatments may also benefit acquired lower motor neuron diseases with a progressive course, high anti-ganglioside GM1 titres and no conduction block. In chronic inflammatory demyelinating polyneuropathy, recent articles have reported interesting immunopathological, electrophysiological and immunochemical features. This syndrome seems to be heterogeneous. Therefore, better criteria need to be defined, particularly so that an informed choice can be made as to the most appropriate treatment. A recent controlled trial has shown that intravenous immunoglobulin infusion may be as effective as plasma exchange in the short-term therapy of chronic inflammatory demyelinating polyneuropathy.