Plasma treatment of polymer surfaces is a well established method for improving surface properties. In this paper the surface structure and adhesive bonding properties of PTFE treated by three types of plasma are reported. The results indicate that different plasma gases have different effects on the surface structure. Argon plasma treatment protected a highly cross-linked honeycomblike structure produced air and oxygen plasma treatment resulted in a surface displaying high aspect ratio protrusions. All experimental plasma treatments caused a marked improvement in overlap shear strength , with the highest shear strength achieved after oxygen plasma treatment. It was found that the overlap shear strength was also influenced by plasma power and plasma treatment time although excessive plasma treatment caused damage to the surface layer leading to decreased shear strength. The change in surface properties and roughened microstructure together contributed to the improvement in shear strength. (C) 2000 IoM Communications Ltd.