Varietal differences in the contents of free sugars, catrotenoids, and free and hydrolyzed amino acids in sweetpotatps were investigated. Based on cluster analysis of the free sugar composition of steamed roots, the lines were classified into 3 groups. Among the 53 entries, 47 lines were classified into group 1 that was characterized by relatively small amounts of fructose and glucose, moderate amounts of sucrose and large amounts of maltose in steamed roots. It was demonstrated that there were 2 breeding lines lacking β-amylase (group 2) and 3 lines with a high hexose content (group 3). Some of the lines with a high hexose content showed a high acid invertase acitivity. The relationship of the maltose content between 2 years was as phenotypically stable as that of the dry matter content. Heat stability of β-amylase and starch gelatinization degree during heating were the major factors controlling the varietal differences in the maltose content. The carotenoid composition of 22 orange flesh lines did not differ among the lines and β-carotene predominated. Retinol equivalents of major cultivars were almost equivalent to the maximum value of carrot cultivars. The largest variability in aspartic acid content among the lines was due to the variability in the free asparagine content.