The mixing enthalpies of formamide and N,N-dimethylformamide with myo-inositol 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 myo-inositol in aqueous sodium chloride solution are negative and become less negative with an increase in the concentration of sodium chloride. In contrast, the values of h(xy) between N,N-dimethylformamide and myo-inositol are positive and become more positive with increasing concentration of sodium chloride solutions. The results are discussed in terms of solute-solute interaction and solute-solvent interaction.