AbstractPhotopolymerizing hydrogels have demonstrated potential for use as a scaffold in numerous tissue‐engineering applications. The majority of photopolymerizing hydrogels are made from purely synthetic polymers. The purpose of this study was to synthesize and characterize photopolymerizing hydrogels derived from the biopolymer chondroitin sulfate in order to enhance the bioactivity of the scaffold and potentially improve tissue regeneration. Methacrylate groups were added to chondroitin sulfate, a major component of cartilage, using glycidyl methacrylate. The gels exhibited viscoelastic behavior typical of hydrogels. Cogels based on chondroitin sulfate and poly(ethylene glycol) demonstrated increasing pore size with increasing concentration of chondroitin sulfate as determined by water content, mechanical strength, and morphology using scanning electron microscopy. The chondroitin sulfate hydrogels degraded specifically in the presence of the enzyme chondroitinase. Chondrocytes remained viable after photoencapsulation and incubation in the biogels, suggesting their possible use for cartilage tissue engineering. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 28–33, 2004