A study was made of the microscopic effects of profound hypothermia on spinal cord of the dog. Samples of cervical, thoracic, lumbar and sacral cord levels of three normal and eight experimental dogs were examined. In the experimental sections the axons and myelin were apparently unaltered, and the number of anterior horn cells was within normal limits. Changes in the experimental sections included the appearance of slight to moderate chromatolysis, hyperchromic, pyknotic neurons, and most commonly, gliosis, which was more evident in the lumbar and sacral cord levels. The findings of the present study were in agreement with the results other authors have reported in studies on ischemia by vascular occlusion. Although the alterations found in the spinal cords of the experimental dogs were not extensive, it is believed that these animals had been subjected to a condition of mild ischemia.