The process of proving that new treatments for peripheral nerve diseases work has often been slow and inefficient. The lack of adequate evidence for some existing treatments has been highlighted by Cochrane systematic reviews. This article uses four different conditions to illustrate the need for more research. Both corticosteroid injections and surgical decompression of the median nerve are efficacious in carpal tunnel syndrome, but whether corticosteroid injections avoid the need for operation needs to be discovered. Corticosteroids are efficacious for Bell's palsy, but the role of antiviral agents needs clarification, which should come from ongoing trials. Intravenous immunoglobulin (IVIg) and plasma exchange are both efficacious in Guillain-Barré syndrome, but corticosteroids are not. More trials are needed to discover the best dose of IVIg in severe cases and whether mild cases need treatment. In chronic inflammatory demyelinating polyradiculoneuropathy, corticosteroids, IVIg and plasma exchange are all efficacious, at least in the short term, but trials are needed to discover whether and which other immunosuppressive agents help. The Peripheral Nerve Society has formed a standing committee, the Inflammatory Neuropathy Consortium (http://pns.ucsd.edu/INC.htm), to facilitate the trials needed to answer the remaining questions in the inflammatory neuropathies.