New lactide-based poly(ethylene glycol) (PEG) polymer networks (GL-PEG) have been prepared by photopolymerization using two nontoxic macromers, triacrylated lactic acid oligomer, emanating from a glycerol center (GL) and monoacrylated PEG. These materials may use as polymer scaffolds in tissue engineering because they provide biodegradable, cell-adhesion resistant, and ligand-immobilizable characteristics. The thermal and mechanical properties of the resulting GL-PEG networks were evaluated and their biodegradability was investigated in phosphate buffered saline (PBS) at 80degreesC. The glass transition temperature (Tg) of all networks after degradation relatively decreased and the trend was similar to those before biodegradation, whereas thermal decomposition temperature (Td(1/2)) increased in all networks to a certain degree. The tensile strength decreased as PEG was incorporated and as the molecular weight and content of PEG increased due to the soft PEG chains. Degradation rate of GL-PEG networks was controlled by the ratio of GL to PEG, and generally the rate of GL-PEG networks was faster than that of GL homonetworks.