Yoqurt products are known to be effective for enhancing health and preventing diseases such as cancers. Such effects are generally believed to be due to actions of polysacchmides in yoqurt products. In this study we have determined compositions of monosaccharides in hydrolysates of commercial yoqrtrt products as the first step of understanding structures of polysaccharides. The yoqtrrt products were ttltracentrifuged, filtered, hydrolyzed in 1M sulfuric acid and neutralized. A portion of the solution was taken and evaporated to dryness, denvatized with TMSI (trimethly- silylimidazole) and analyzed by GC/MS. We found that the monosaccharides were fructose, glucose, and galactose. Their compositions were variant among several yoqtrrt products.