Abstract: A process for the manufacture of polyolefin film, especially high density polyethylene film, is disclosed. In the process molten polyolefin is extruded through an annular die and the tubular molten polyolefin film so formed is withdrawn from the die, expanded, cooled and flattened. The process is controlled so that (a) the ratio of the diameter of the expanded tubular film to the diameter of the annular die is in the range 1.8:1 to 5:1, (b) the frost line formed as the polyolefin cools is at least four feet from the annular die, (c) the completion of the expansion of the tubular film is juxtaposed to, and prior to, the formation of the frost line. The ratio of diameters and the frost line are co-operatively adjusted with the rate at which the film is withdrawn from the annular die and the temperature at which the molten polymer is extruded through the die so that the Elmendorf tear in the machine direction is at least 15 gms./mil.