Isobaric vapor-liquid equilibria were measured for the system o-xylene + amyl acetate + nonane and for three constituent binary systems at the pressures 101.32, 79.99, 53.33, and 26.66 kPa. The measurements were made in a semi-microebulliometer. Nonane formed minimum boiling azeotropes with o-xylene and amyl acetate while the binary system o-xylene + amyl acetate was nonazeotropic. The Wilson model was used to correlate the binary boiling temperature (T)-composition (x) data. The T-x data of the ternary system were found to be well predicted by the Wilson model, giving significantly better results than the UNIFAC method.