Enthalpies of dilution of glycine, l-serine and l-valine dissolved in mixtures of water and N,N-dimethylformamide (DMF) with mass percent of DMF 0, 5, 15, 25, 35 and 45, respectively, have been measured with an LKB 2277 Bio Activity Monitor at 298. 15 K. It was found that pairwise enthalpic interaction coefficients h(2) of glycine and l-serine decrease with increasing DMF content in mixed solvents, while the influence of DMF on h2 values of l-valine is not obvious.