A Calvet type calorimeter was used for measurement of partial and integral enthalpies of mixing of Ag-Ga-Sn alloys. The Ag-Ga binary alloys have been studied with 0 < x(Ag) < 0.79 composition and in the 803-1073 K temperature range. The mixing enthalpies at 803 K of Ga-Sn binary alloys have been determined for x(Sn) < 0.35. The Ag-Ga-Sn ternary liquid alloys have been investigated at 803 K along the following sections: x(Ag)/x(Ga) = 1/3, x(Ag)/x(Ga) = 0.36/0.64, x(Ag)/x(Ga) = 1/1, x(Ga)/x(Sn) = 1/3, x(Ga)/x(Sn) =1/1, x(Ga)/x(Sn) = 0.65/0.35 and x(Ga)/x(Sn) =3/1. Experimental data were used to obtain the binary interaction parameters by using the Redlich-Kister polynomial for the Ag-Ga binary system, while the Redlich-Kister-Muggianu method was used to determine the ternary interaction parameters for the Ag-Ga-Sn system. The experimental values and the fitted curves were compared with those predicted from the Muggianu and Toop methods. (C) 2011 Elsevier B.V. All rights reserved.