Results of Monte Carlo simulations are presented for the equilibrium swelling of athermal (hard-core) polymeric gels. The networks investigated in this study are defect-free and exhibit strand lengths that range from small to moderate. It is shown that at equilibrium increasing pressure and strand length leads to higher solvent holdups by the gel. Computer experiments of swelling of gels in binary solvent mixtures indicate that the gel absorbs preferentially the component having the smaller molecular excluded volume. A simple mean-field theory is also presented to describe the swelling of athermal networks. Agreement between theory and simulations is good.