The solubility of poly(methyl methacrylate) in acetone, expanded by carbon dioxide, was studied at 20 degreesC for a variety of molecular weights and architectures. The suitability of the Gas Anti-Solvent method for fractionation of poly(methyl methacrylate) was investigated with positive results. The threshold pressure for precipitation of various monodisperse molecular weights was investigated, and the effectiveness of this technique to fractionate a polymer with a broad molecular weight distribution was evaluated. The pressure required to precipitate polymers was found to be low, generally below 60 bar. (C) 2003 Elsevier Science Ltd. All rights reserved.