Recent calorimetric investigations of enthalpies of mixing in Liquid alloys and of enthalpies of formation of intermetallic compounds have brought important information in systems which present very strong heteroatomic interactions. In the light of these new data, it is possible to discuss the Miedema's formulation of enthalpies of formation and of mixing, the short range order in the Liquid alloys and to propose a simple modeling of the enthalpy of mixing in transition metal-sp metal alloys.