Poly(ethylene glycol) (PEG) macromers terminated with acrylate groups and semiinterpenetrating polymer networks (SIPNs) composed of poly(epsilon-caprolactone) (PCL) and PEG macromer were synthesized and characterized with the aim of obtaining a bioerodible hydrogel that could be used to release tetracycline HCl for local antibiotic therapy administered peroperatively. Polymerization of PEG macromer resulted in the formation of crosslinked gels due to the multifunctionality of macromer. Noncrosslinked PCL chains were interpenetrated into the crosslinked three-dimensional networks of PEG. Glass transition temperature (T-g) and melting temperature (T-m) of PCL in the SIPNs were inner shifted, indicating interpenetration of PCL and PEG chains. It was found that water content increased with increasing PEG weight fraction due to the hydrophilicity of PEG. Drug release can be controlled by weight fraction of PEG in the PCL/PEG SIPNs, concentration of PEG macromer in the SIPNs preparation, and the nature of PEG.