The peripheral nervous system is frequently impaired in patients who have cancer. This impairment often results from toxicity of treatment but may also be due to direct invasion by tumor or may be part of a paraneoplastic syndrome. This review summarizes the recent literature regarding peripheral neuropathies and myopathies that are seen in patients with cancer. Highlights include the neuromuscular toxicity of some of the newer chemotherapeutic agents and immune mediators such as taxol and interleukin-2; a discussion of some of the agents being investigated for chemoprotection and rescue; an assessment of the evidence supporting the concept of motor neuron disease as a paraneoplastic disorder; and an interesting case report of megakaryoblastic leukemia invading peripheral nerves. Also summarized are some nice reviews and prospective studies of the toxicity of more conventional treatments.