This work describes a comprehensive study of hydrogels based on polyethylene glycol diacrylates (PEGDAs) with the molecular weight (MW) range of 400-2000. The blends of low- and high-molecular weight PEGDA macromers with different ratios were photopolymerized under visible light irradiation, using a blue light sensitive photoinitiator Irgacure819, at the total polymer concentration of 60 wt %. Swelling ratios, wetting property, elastic moduli, transparency, and the microstructure of the resulting hydrogels were investigated. Among them, equilibrium water contents, hydrophilicity, and mesh size of the hydrogels increased while the elastic moduli decreased when increased the PEGDA MW or the content of higher MW PEGDA in the blends. Most of the hydrogels possessed excellent transparency in visible region. The viability of L929 cells on the surface of hydrogel was also estimated. All the selected hydrogels exhibited a relatively high proliferation rate, which demonstrated this hydrogel system with photoinitiator Irgacure819 had good biocompatibility. These results show the properties of PEGDA hydrogel could be easily adjusted by varying PEGDA MW or the ratios of low- and high-MW macromers in the composites. It could be helpful for the design of proper PEGDA hydrogels in the applications as tissue engineering or drug delivery system. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 531-540, 2011