The AgPbSb ternary system and its low order AgPb, PbSb and AgSb binary systems have been evaluated thermodynamically by applying the Calphad method. A set of the Gibbs energy parameters of the various phases in the individual systems has been obtained through a computer-operated optimization procedure with the available experimental information. The calculated thermodynamic quantities and phase equilibria are in close agreement with the literature values. Parameters describing the Gibbs energies of all the phases used in this calculation and the calculated results are presented.