The enthalpy change of alloys of Al-Si system having hypoeutectic composition (Si content nSi=0; 1.92; 6.26; 9.22%) is measured by the method of adiabatic drop-calorimetry over the temperature range of 380-1200 K relative to 'base temperature equal to 293.15 K. Specific heats of alloys in liquid state are computed by using the results of measurements. The correlation of the latter with the data on density of melts of Al-Si system testifies a possibility for effect of microhomogeneous structure of melts on their thermodynamic properties.