In vitro degradation behaviors of composite materials composed of poly-l-lactide (PLLA) and bioactive glass (BG) were systematically investigated up to 20 weeks in phosphate-buffered solution (PBS) at 37 A degrees C. The properties of PLLA/BG composites and PLLA materials, including weight loss, bending strength and modulus, shearing strength, polymer molecular weight and its distribution, and the morphologies, were investigated as a function of degradation time. The change of the pH value of the PBS media was also detected. The results showed that the presence of the bioactive glass modified the degradation of the matrix polymer. The degradation rate of the PLLA/BG composites was slower than the degradation rate of the sole PLLA materials.