AbstractDamage evolution in a commercial magnesium sheet alloy (Mg-3Al-1Zn-0.3Mn) at room temperature is investigated. Kahn tear tests were performed to characterize the crack extension behaviour. Scanning electron microscopy of the fracture surfaces revealed flat inclined areas and the absence of cracked particles and dimples. Post-mortem synchrotron tomography of a stopped crack was used to further identify the predominant damage mechanism in the specimen’s ligament. Nucleation of submicrometre-voids, a micro-void sheeting mechanism and the absence of classical void growth could be identified.