Isobaric vapor-liquid equilibria were measured for the three binary systems of methyl butyrate, methyl pentanoate, and methyl hexanoate with propannenitrile at a constant pressure of 93.32 kPa. The measurements were carried out with in small recirculating still. The composition of condensed vapor and liquid phases was calculated indirectly from density measurements made with a vibrating tube densimeter. The thermodynamic consistency of the data was verified with two point-to-point tests. Activity coefficients calculated from experimental data have been correlated by several models and compared with predictions of group-contribution models. These systems exhibit positive deviations from ideality. The methyl butyrate + propannenitrile system formed a minimum boiling azeotrope.