The temperature and composition dependences of the excess enthalpy, h(E), have been calculated using the NRTL model for mixtures of n-heptane with the hydrogen-bonded liquids of acetic acid, propionic acid, amylamine and n-octanol. Reduced and partial molar excess enthalpies were also calculated, The temperature-dependent parameters of the NRTL model, estimated directly from h(E) data for more than one isotherm, were used in the calculations. The overall deviations of all the experimental data points fall in the range 0.5-6.5% which shows highly satisfactory correlation of h(E) data with the model. The temperature range for the mixtures is 285.15-330.15 K. The surfaces of excess enthalpy functions facilitate better understanding of the thermodynamic properties of the hydrogen-bonded mixtures. The NRTL model is a reliable thermodynamic model for studying the hydrogen-bonded mixtures in a qualitative and quantitative manner.