We report isobaric vapor-liquid equilibrium measurements of binary systems of methyl butyrate, methyl pentanoate, and methyl hexanoate with acetonitrile at a constant pressure of 93.32 kPa. The measurements were carried out with a small recirculating still. The composition of condensed vapor and liquid phases was calculated indirectly from density measurements made with a vibrating-tube densimeter. These systems exhibit positive deviations from ideality. 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.