In order to clarify why orthopedic complaints such as lumbago are ameliorated by hot-spring bathing, serum levels of sialic acid and fucose, which form glycoconjugates and are markers of connective tissue metabolism, were measured before and after each hot-spring bathing. No changes were observed in serum sialic acid for persons who took hot-spring bathing more than three times per day for 10 days. However, many of them showed a decreasing tendency in serum fucose level after bathing. Although it is not clear why this tendency occurs, it strongly suggests that hot-spring bathing influences on connective tissue metabolism.