Influence of hot-bath upon fatigue reaction was studied by estimation of KES and D. O. K. levels in matutinal urine of the operated cases, after five minutes of bathing (42° to 43°C) once every day from the seventh postoperative day. Those cases were ambulated early after gastrectomies for ulcer or cancer and cholecystectomies during intermediate stage of cholelithiasis. Results obtained were as follows. 1) In the group which took bath and ambulated early after gastrectomy for ulcer and cholecystectomy for stone, the relieve of fatigue was faster than the control group, and was much as compared with the group ambulated ordinarily. 2) In the group gastrectomized for cancer the recovery from fatigue was rather retarded in the second week in comparison with non-bathing group, and became almost equal in the end of third week. Comparing with ordinary group, it was nearly same in the second week and became slightly better in the third week, without satisfactory rehabilitation in those three groups. Intention should be paid on the selection of case for taking thermal-bath in the gastric cancer patients uniformly after seventh day of operation.