In a selected series of twenty-three RA patients, aged from 23 to 56 years, mean 41, the neurophysiological functions of six sensory nerves were measured and the results were correlated with clinical and laboratory data. Significant changes in the functions of one or more nerves were found in 10 patients, 2 of whom had no symptoms of clinical neuropathy. There was a highly significant correlation between neurophysiological symptoms and clinical neuropathy symptoms, although the combination of the clinical and electrophysiological findings was variable. On the other hand, there was no significant correlation between neurophysiological/neurological findings and clinical/laboratory data (age, sex, duration of disease, stage of disease, rheumatoid factor and erythrocyte sedimentation rate). Manifest or sub-clinical mono-neuropathies in n. medianus were found in 5 patients. In the light of these results it would seem in order to recommend the inclusion of an electro-neurophysiological examination of the medianus nerves of RA patients in routine diagnostic procedures.