The paraproteinemia is a disorder in which a single clone of plasma cells (monoclonal gammopathy) is responsible for the proliferation of monoclonal proteins (M-proteins). Approximately 10% of patients with idiopathic peripheral neuropathy have monoclonal gammopathy. Some M-proteins have the properties of an antibody to the components of peripheral nerve myelin, but the pathophysiological relationship between the neuropathy and the M-protein is often obscure. The relationship between peripheral neuropathy and monoclonal gammopathy requires the appropriate neurological and hematological investigations for precise diagnosis and treatment. In this review, we provide an update on the causal associations between peripheral neuropathy and monoclonal gammopathy as well as characteristics of clinical and electrophysiologic features.