Abstract: A method and apparatus for slitting a moving thermoplastic film. A rotating slitting roll, provided with a plurality of spaced-apart heated blades circumferentially arranged in a pattern, presses the film against a backing member while the film is under tension and in line-contact with the roll. The pressure and heat of the blades fusion-slits the moving film, which may then be stretched to spread the slits and in the case of orientable film to orient the film in the direction of stretch. The slits may be made in either the machine or cross-machine direction. Where continuous slits are made, tapes or ribbons are formed. Where the slits are discontinuous, an aperture film results.