Monolithic 5064.6 mm ID poly(styrene-co-divinylbenzene), poly(glycidyl methacrylate-co-ethylene dimethacrylate), and poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) columns have been tested in the high-performance liquid chromatography (HPLC) separation of polystyrenes and poly(methyl methacrylate) standards. The separation process involves precipitation of the macromolecules on the macroporous monolithic column followed by progressive redissolution and elution utilizing a gradient of the mobile phase. While very good separations of individual components of mixtures of both polystyrenes and poly(methyl methacrylates) can be readily achieved using poly(styrene-co-divinylbenzene) monolith, methacrylate-based columns do not afford good separations under identical conditions. This unexpected finding appears to be the result of significant differences between the porous properties and chemistries of the two types of monolithic materials.