An underlying carcinoma is an important differential diagnosis in peripheral neuropathy. While direct compression and infiltration of spinal roots or peripheral or cranial nerve trunks or branches can be identified easily when they occur in association with established malignancy, their diagnosis when they are presenting features may be difficult. In paraneoplastic sensory neuronopathy autoantibodies to neuronal antigens have become useful diagnostic markers for an underlying carcinoma, especially anti-Hu antibodies. Strong circumstantial evidence suggests that these antibodies form part of an autoimmune response which is responsible for the pathogenesis of some of these syndromes. Neuropathy appearing during the course of treatment of carcinoma may be due to radiation-induced damage or the neurotoxic effects of some chemotherapeutic agents. Neurotrophic factors are being investigated as a strategy for reducing the neurotoxic effects of these agents.