AbstractIn the present study we evaluated the in vitro and in vivo degradation of an in situ forming biodegradable implant. For this purpose we used a poly(D,L-lactide-co-glycolide) (PLGA) polymer dissolved in biocompatible solvent dimethylsulfoxide (DMSO). The evolution of the morphology, mass loss, water gain, hollow fraction, and molecular weight of the implants degraded in both conditions was investigated and compared. Implants presented a porous morphology, being denser and having channels in vivo, as seen by scanning electron microscopy. Erosion in vivo of implants involved the appearance of new small pores, while an increase of the size of preexisting pores was seen in vitro. Mass loss and molecular weight –as a measure of erosion and degradation, respectively– decreased much faster in vivo than in vitro, suggesting the importance of environmental conditions on these processes of porous biodegradable matrices formed in situ.