A thermodynamic analysis of the phase equilibria in the Pb-Sn-Sb ternary system was conducted. A regular solution approximation based on a two-sublattice model was adopted to describe the Gibbs energy of formation of the individual phases in the binary and ternary systems. In the case of some component binary systems, the effect of pressure also was considered. Experimental data obtained by differential thermal analysis (DTA) and electron probe microanalysis (EPMA) in the present study, along with literature data on phase boundaries and thermochemical properties, form the basis for the evaluated thermodynamic parameters used in the calculation. Calculated and experimental phase boundaries agree fairly well.