By means of an optimization procedure, the ternary Ag-Au-Pb system has been assessed. All available experimental data of the ternary system and the results derived from thermodynamic descriptions for the three limiting binary systems are used. For the Ag-Au and Au-Pb systems, optimized Gibbs energy expressions were taken from the literature. A new assessment of the binary Ag-Pb system based on our calorimetric investigations is presented in this paper. Calculated phase diagrams and some calculated thermochemical functions for the binary Ag-Pb and the ternary Ag-Au-Pb systems are compared with experimental data. (C) 2010 Elsevier B.V. All rights reserved.