Thermographic analyses before and after operation were studied in 30 patients with root compression syndrome. Of these, 12 patients had cervical radiculopathy, and 18 patients had lumbar disc herniation. All of patients were diagnosed the single level lesion by clinical findings, myelogram, and MRI findings. The accordance rate of thermotome with clinlcal symptome and MRI findings was investigated. The manifestation of thermographic cold area coincided with the pain-distribution on the surface in most cases. The degree of compression in dural tube on MRI correlated with appearance rate of cold area on thermogram. However, the degree of temparature of the thermographic cold area didn't correlate with the MRI findings. The asymmetric thermographic cold area was reduced or disappeared by the decompression surgery. Therefore, thermographical examination is useful to evaluate the result of surgical treatment and follow-up study.