The enthalpies of mixing of formamide with D-mannitol and D-sorbitol and their respective enthalpies of dilution in aqueous sodium chloride solution have been determined by using flow-mix-isothermal microcalorimetry at 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (h(xy), h(xxy), and h(xyy)) according to the McMillan-Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients (h(xy)) between formamide and D-mannitol in aqueous sodium chloride solution are positive and become more positive with an increase in the molality of sodium chloride. In contrast, the h(xy) between formamide and D-sorbitol varies from a negative value to a positive one and increases with the elevated molality of sodium chloride. The results are discussed in terms of solute-solute interaction and solute-solvent interaction.