Phase and chemical equilibria in the quaternary ethyl ethanoate + ethanol + propyl ethanoate + propanol system and in all six binary subsystems have been investigated at two isotherms, namely at 323.15 and 348.15 K. In total, 116 quaternary experimental points were determined. The binary data were correlated by means of the NRTL model using a robust approach and the maximum likelihood procedure. The binary parameters obtained were used for prediction of vapour-liquid equilibria in the quaternary system and results show a good agreement of calculated and experimental data. The three-dimensional phase diagrams for the quaternary system have been constructed with use of transformed compositions. (C) 2012 Elsevier B.V. All rights reserved.