The deformation behaviour during rolling is studied by small-angle X-ray scattering, density measurement, and investigation of the debris after fuming nitric acid treatment. Crystallinity and mechanical properties are compared with corresponding results on drawn material. Results obtained on quenched and annealed films of two polyethylene brands, Fortiflex and ACX, show many similarities in properties between rolled and drawn samples of similar draw ratio, i. e., a progressive lattice orientation, the appearance of a new long period different from that of the original film at λ=2 in Fortiflex and at λ=1.5 at ACX, decrease in crystallinity of annealed films, and constancy in quenched material during rolling. Therefore, it is concluded that, as in the case of drawing, the basic structure transformation during rolling is the destruction of lamellae with pulling out of microfibrils. Significant differences exist, however, between the two cases in ultimate tensile strength and in ultimate elongation.