A vibrating tube densimeter and sound analyzer Anton Paar model DSA-5000 has been used for the measurement of densities, rho, and speeds of sound, c, of N-methyl-phenylamine (N-methylaniline) + heptane, or + cyclohexane, or + toluene mixtures at (293.15 to 303.15) K and atmospheric pressure. From these data, we have obtained excess molar volumes, V-m(E), at the three temperatures and excess functions for c and the isentropic compressibility, K-s at 298.15 K. V-m(E) results reveal the existence of structural effects in alkane solutions and of interactions between unlike molecules in systems with toluene. N-Methylaniline + hydrocarbon mixtures have been characterized in terms of the ERAS model. The theory provides a good representation of excess molar enthalpies, H-m(E), and describes correctly the relative variation of V-m(E). ERAS calculations show the importance of the physical interactions in the studied systems, which is consistent with the experimental H-m(E), and V-m(E) data.