Initiation of cavitation upon drawing of pre-oriented polypropylene films has been investigated via insitu small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD) techniques. The macroscopic strains for the initiation of the cavitation epsilon(cav) and for the initiation of crystal shear epsilon(cs) have been estimated from in-situ SAXS and WAXD tests respectively. Local crystal shear appears before cavitation upon drawing in machine direction (MD) has been revealed via comparison of epsilon(cs) and epsilon(cav). The initial size of the cavities in MD is larger than the long period of crystalline lamellae while the size in transverse direction is inversely proportional to the relative fraction of daughter lamellae. Macroscopic critical stresses for the initiation of cavitation sigma(cav) and for the initiation of crystal shear sigma(cs) have been estimated as well. The critical stress sigma(cav) is independent on the crystallinity, whereas sigma(cs) increases with increasing crystallinity. The mechanism for the initiation of cavitation has been proposed, i.e. the cavitation is initiated by the breakage of crystalline lamellae at the anchor point of the daughter lamellae. (C) 2017 Elsevier Ltd. All rights reserved.