Isobaric vapor-liquid equilibrium (VLE) measurements are reported for binary mixtures of N-methylacetamide and N,N-dimethylacetamide with cumene at 97.3 kPa. The data were obtained using a vapor recirculating type (modified Othmer's) equilibrium still. Both mixtures show positive deviation from ideality. Both the systems form azeotropes. The experimental data obtained in this study are thermodynamically consistent according to the Herington and Black tests. The activity coefficients have been satisfactorily correlated by means of the NRTL equation.