A clinical and pathological report of a patient who died 15 days after suffering a classic heat stroke is presented. The clinical picture was of a flaccid quadriplegia with anhidrosis and sphincter disturbance. The most severe pathological lesions were to be seen in the anterior and intermedio-lateral horns of the spinal cord. Hyperthermia was the only physiopathological mechanism demonstrated in the patient. It is suggested that the motor neurons and vegetative neurons of the spinal cord are specially sensitive to hyperthermia.