The equilibrium swelling ratios of a slightly crosslinked polymethylmethacrylate sample in toluene-ethanol and acetone-water solvent-non-solvent mixtures have been determined volumitrically, The values of swelling ratio Q go through a maximum at the volume fraction of the non-solvent, γ=0.1%(ethanol) and 0.02(water) for the two systems respectively, in parallel with the viscornetric and osmometric behavior observed in dilute solutions.