The Elastic Incoherent Structure Factor (EISF) for neutron scattering in liquid crystals has been interpreted theoretically by evaluating the correlation functions for the molecular reorientation according to the diffusion model for highly ordered fluids. It is shown that the available experimental data are compatible with the orientational distribution function predicted by the Maier-Saupe model for uniaxial mesophases provided that the long time behaviour of the correlation functions within the time scale of the experiment be properly considered.