Vapor phase photografting of acrylic acid (AA) was carried out onto low density polyethylene(LDPE) films on which benzophenone(BP) was previously coated. By means of thermal analysis, it was found that the grafting occurred mainly in amorphous region of polyethylene up to a specific graft yield. The change of mechanical properties, hydrophilic properties and morphology of grafted films were compared with the original films.