The voltage sensitivity and concentration dependence of single channel conductance at the motor end-plate in the presence of different alkali cations have been compared with the predictions of different permeation models. The models have been developed, using the diffusional approach, to cater for three cations and anion permeability has been assumed to be insignificant. It was found that a neutral site channel model provided the best fit to the experimental data. The analyses also implied a high field strength sequence for the equilibrium selectively of the sites.