Results of grand canonical Monte Carlo (GCMC) simulations of methane, ethane, propane and their binary mixtures in the zeolite silicalite are presented. The simulations show good agreement with experimentally obtained isotherms and isosteric heats. The binary simulations agree well with predictions made using the Ideal Adsorbed Solution (IAS) theory. This indicates that these light hydrocarbons behave ideally within the silicalite pores, in agreement with previous experiments [J.A. Dunne, M. Rao, S. Sircar, R.J. Gorte, A.L. Myers, Langmuir 13 (1997) 4333-4341]. All three species prefer to locate within the channel regions of silicalite, occupying the spacious but energetically unfavorable intersection regions only at the highest pressures.