The author proved that consumption of iodate by proteinfree serum filtrate, an index of total reductive substance in serum filtrate, was increased after a radioactive thermal bath of Misasa (400-700×10(-10) Curie units Rn per liter), at a temperature of 40°～45℃ for five minutes. Reduced glutathion in blood showed little change, but oxidized and total glutathion tend to rise and decreased only temporarily. Reduced ascorbic acid in blood and urine increased after the radioactive thermal bath, but the oxidized and total ascorbic acid decreased after a temporal increase. After the thermal. bath a tendency of fall in reduced and oxidized ascorbic acid content was observed in liver, lung, and adrenal glands, and a tendency of rise was shown in kidney, spleen, skin and musclein albino rats. By a series of daily successive thermal baths a fall in ascorbic acid content was observed in most of the organs examined in the first week (on the fourth day) and then a reactive increase was shown during the second week.