The longtime self-diffusion of spherical polybutadiene latex particles in water was measured using the pulsed field gradient NMR technique. The particles were highly charged due to the adsorption of anionic surfactant. The volume fraction dependence of the self-diffusion was measured. Also the longtime selfdiffusion coefficient was measured as a function of the concentration of surfactant at a fixed latex volume fraction. Comparison of the results with theoretical predictions showed some qualitative agreement, but at a relatively low volume fraction, deviations from the theory were observed. The self-diffusion coefficient at infinite dilution obtained by extrapolating the experimentally observed values down to zero volume fraction was shown to be consistent with the self-diffusion coefficient obtained from dynamic light scattering.