In order to study the effect of bathing for 10 minutes, 34℃ and 40℃ in temperature, in the hot spring in Misasa on plasma metabolites of rats which took a bath once daily for one, two and four weeks, the body weight and the catecholamine, free fatty acid(FFA) and glucose contents in plasma were measured after serial bathing. The body weight tended to decrease by serial bathing compared with non-treated rats. Plasma noradrenaline (NA) content decreased slightly after one and four weeks-serial bathing, but no change was observed after two weeks-serial bathing. Adrenaline content showed the same tendency to decrease as NA content after one and four weeks-serial bathing, but it increased slightly after two weeks-serial bathing. Plasma FFA contents increased by serial bathing compared with those in controls. As to plasma glucose
content, a slight decreasing tendency was observed after four weeks-serial bathing although no change was observed after one and two weeksserial bathing.