Thermal therapy using far-infrared ray dry sauna was performed for patients with chronic fatigue syndrome (CFS). Symptoms such as fatigue, pain, and low-grade fever were dramatically improved on two patients. And prednisolone administration was discontinued and became socially rehabilitated 6 months after discharge. On other 11 patients with CFS, physical symptoms such as fatigue and pain improved, too. Furthermore, we reported that repeated thermal therapy had relaxation effect and diminishes appetite loss and subjective complaints in mildly depressed patients. These results suggest that repeated thermal therapy may be a promising method for the treatment of CFS.