Molecular dynamics simulations have been carried out in order to investigate the adsorption and permeation phenomena of butane isomers through ZSM-5 membranes. Using the muVT ensemble configurational-bias Monte Carlo technique, we are able to determine the preferred locations of the butane isomers in the ZSM-5 channels. In permeation simulations, using the muVT ensemble non-equilibrium molecular dynamics method, the permeate fluxes of the butane isomers are obtained. We find that the permeabilities of the n-butane calculated from the permeate fluxes increase with increasing temperature. The density of n-butane in the ZSM-5 decreases in the permeation direction with a similar pressure-density relationship to that measured by the equilibrium adsorption isotherm of the n-butane.