Abstract Three types of oligo(ethylene glycol) dimethacrylate were polymerized by seed polymerization. The gel beads so prepared had a narrow size distribution and were macroporous. The columns packed with gel beads were suitable for aqueous size-exclusion chromatography for polysaccharides, proteins and other hydrophilic polymers. The hydrophilicity of the gel beads was almost equal to that of 2-hydroxyethyl methacrylate-ethylene dimethacrylate copolymer beads which are usually used for aqueous size-exclusion chromatography.