Nine patients with peripheral neuropathy and monoclonal gammapathy are presented (4 multiple myeloma, 5 Waldenström's macroglobulinemia). Two patients had tremor and ataxia. All patients had delayed nerve conduction and increased cerebrospinal fluid protein. Symptoms of neuropathy preceded detection of serum protein abnormalities in seven cases. Nerve fiber lesions involved myelin and axons. Biphasic myelopathy with uniform separation of myelin lamellae was observed in one case of Waldenström's disease. Amyloid stains were negative. Treatment was successful in one of four patients. 185 cases of peripheral neuropathy with monoclonal gammapathy are reviewed. Pathogenic role of microvascular changes, amyloid depositions, antimyelin antibody is discussed. The role of anti MAG antibody remains unresolved. Nerve damage due to another cause is possible. The paraprotein and the neuropathy may not be directly related but both caused by the underlying condition.