The proton spin-lattice relaxation time,T1, has been measured for a series of mixtures of benzene in perdeuterobenzene for the liquid in equilibrium with its vapour over the temperature range from below the normal freezing point up to the critical temperature. The two contributions toT1due to interactions within the molecule (T1 intra) and between molecules (T1 inter) have been separated and are found to be very different in magnitude and in variation with temperature. The variation and magnitude ofT1 intercorrelates well with other translational motion dependent properties such as self diffusion and viscosity. The correlation ofT1 intrawith other re-orientation dependent properties such as deuteronT1and Rayleigh scattering is poor.