In this paper, isobaric vapor liquid equilibrium 500 (VLE) data for the binary system of gamma-butyrolactone + succinic anhydride were measured at pressures of 20.0, 30.0, and 40.0 kPa by a modified Rose still. There was no azeotropic phenomenon observed at each pressure. A thermodynamic consistency test is a way to verify the reliability of the experimental data. The VLE data were tested by a Herington area test and Van Ness point test. Then, the VLE data showed a good correlation with nonrandom two-liquid (NRTL) and Wilson activity coefficient models.