The in vitro rate of degradation was purposely affected by covalently grafting the surface of poly(l-lactide) (PLLA). PLLA films were surface modified by our vapor-phase nondestructive photografting technique. Films were grafted for 20 min with one of the following monomers: acryl amide (AAm), N-vinyl pyrrolidone (VP), or acrylic acid (AA) and thereafter incubated in vitro in a phosphate-buffered saline solution at 37 degrees C for 154 days. The films were studied with contact angle measurements, SEM, ATR-FTIR, SEC, and DSC. The analyses verified that the in vitro rate of degradation was enhanced and that the grafted surface layer did remain covalently attached to the surface during the initial stages of incubation.