The quasi-elastic and inelastic spectra of 10 a neutrons scattered by MBBA in its nematic phase at various angles are reported. For small energy transfers the measured spectra have been resolved in the quasi-elastic peak, whose broadening as a function of the momentum transfer allows an evaluation of the self-diffusion coefficient, and in a broader underlying contribution due to molecular rotations. It has been found that the gas model fits very well the inelastic scattering.