AbstractIn an attempt to provide polyolefins such as low‐ and high‐density polyethylene and polypropylene with autohesive properties, hydrophilic monomers such as methacrylic acid (MAA), acrylic acid (AA), and 2‐(dimethylamino)ethyl methacrylate (DMAEMA) were photografted onto their surfaces. The wettabilities of the grafted plates stayed constant above full coverage of the substrate surfaces with grafted polymer chains, except for the AA‐grafted plates. The amount of absorbed water for the grafted layers formed increased with an increase in the number of grafted polymer chains. The autohesive strength increased with an increase in the wettability and water absorptivity of the grafted plates as well as the temperature and load on heat pressing. For all grafted plates substrate breaking at autohesive strength measurements was observed for grafted amounts 2–3 times as much as those at adhesive strength measurements. The substrate breakings for the HDPE and PP plates photografted with AA and DMAEMA at adhesive strength measurements were observed at lower grafted amounts compared with those photografted with MAA. This study has made it clear that the photografting of hydrophilic monomers onto polyolefin materials can markedly enhance autohesivity without any adhesives as well as the adhesivity for high grafted amounts. Therefore, polyolefin materials with improved autohesivity and adhesivity can be widely applied in adhesive fields, including for novel uses. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2244–2252, 2003