Intensive evaluation of 205 cases of undiagnosed neuropathy in a center with special approaches and facilities permitted classification of 76% of the patients. Inherited disorders accounted for 42% of the series, 21% of the patients were shown to have inflammatory-demyelinating polyradiculoneuropathy, and 13% had neuropathies associated with other disorders. A considerable improvement in diagnosis was possible from evaluation of the kin of the patients with undiagnosed neuropathy. Analysis of the frequency and type of various sensory symptoms also was helpful in distinguishing between acquired and inherited neuropathies.