Abstract: A method and apparatus for biaxially stretching plastic material extruded in tubular form to produce a plastic film suitable for subsequent shrinking around an article or articles in packaging processes and the like. An extruded tube of plastic is passed through two spaced apart sets of rollers which are movable axially of the tube relative to each other and the extruder nozzle to increase the pressure of a gas introduced into the tube and forming a bubble between the sets of rollers, the increased pressure increasing the diameter of the bubble between the sets of rollers to a desired amount which stretches the tube transversely to a predetermined degree at the same time it is being stretched longitudinally by the differential rotational speeds of the two sets of nip or squeezing rollers rotating at different speeds.