Neither clinical nor laboratory evaluation can distinguish occupational neuropathies from neuropathies due to other causes. A worker may suffer either from mechanical injury of individual nerves or from a toxic polyneuropathy that is usually axonal in type. A thorough occupational and environmental history and the recognition of clusters of cases are important in determining the diagnosis. Electrophysiologic studies are helpful in detecting neuropathies in patients who have been occupationally exposed to neurotoxins but have no symptoms. Prevention of occupational neuropathies depends on clinical vigilance, industrial hygiene surveys, biologic monitoring and periodic examination of workers exposed to neurotoxic chemicals. The development of more sophisticated methods of prevention and early detection of peripheral nerve involvement depend on understanding the mechanisms of action of toxins and the pathophysiology of the lesions they cause.