A sweetness potency was found in novel α-L-aspartyl dipeptide analogs which were quite stable on heating in an aqueous solution. The insertion of a methylene group into the peptide chain of α-L-aspartyl dipeptide esters mostly decreased the potency of the sweetness. However, the further exchange of the carbonyl and oxygen functions with each other on the ester group of a C-terminal β-alkyl-β-aminopropionic