The study of temperature dependences of N-Methylpyrrolidone dipole moments (NMP) has been carried out in its liquid state and in dilute aqueous solutions. The dipole moment and the Kirkwood factor temperature dependences suggested the NMP to be weakly associated liquid. The NMP dipole moment in aqueous solutions calculated by Buckingham statistical theory of the dielectric polarization was 4.12 D at 25 deg.cent. indicating the absence of the expected polarization influence of the polar water molecules.