An experimental sub-human primate model of central pain has been discovered. Macaques have been observed to predictably mutilate their hindlimb after undergoing a contralateral midthoracic anterolateral cordotomy or hemisection. Similar bizarre behavior has been observed in monkeys after total limb de-afferentation. The same behavior occurred in one fortuitous case of a monkey with a pathological upper lumbar spinal syrinx. These phenomena suggest a remarkable parallel with the severe disturbing paresthesias in humans subjected to the same neurological insult. The working hypothesis is that these phenomena result from interruption of transmission to and via the spinothalamic tract, which results in chronic abnormal discharge patterns at a diencephalic level. Various combinations of neurosurgery of spinal and peripheral levels have indicated that these paresthesias are largely independent of spinal mechanisms. BIBLIOGRAPHIC REFERENCES: Levitt, M. and Levitt, J.H.: Disturbing sensations of central neural origin in monkeys. Fed. Proc. 36:538, 1977. Levitt, M. and Levitt, J.H.: Primate paresthesias: specific and nonspecific ascending spinal mechanisms. Neurosc. Abstr. 3: , 1977.