The enthalpies of mixing of three kinds of aqueous amino acid solutions (glycine, L-alanine, and L-serine) with aqueous sorbose solution and aqueous fructose solution and their respective enthalpies of dilution have been determined at 298.15 K using a 2277 flow microcalorimetry. The experiment data have been analyzed in terms of McMillan-Mayer formalism to obtain the enthalpic virial coefficients for heterotactic interaction. The results have been interpreted from the point of view of solute-solute interactions.