In our hospital, 134 patients (28 male, 106 female, 10-82 years of age) were diagnosed as having chronic fatigue syndrome (CFS). Some patients had mild elevation of antibodies against Epstein-Barr Virus and immunologic abnormalities (natural killer cell dysfunction and high rates of skin reactivity to house dust, pollen, drugs and common food). In the patients with immunologic abnormalities, we found decreases in serum concentrations of arachidonic acid and dihomogamma-linolenic acid. A Kampo medicine, Ren-Shen-Yang-Rong-Tang was used in the management of 134 patients and 98 patients returned to work or school.