Fracture behaviour of an ultra thin Aluminium foil (with a thickness of 6.6 μm) was studied. For very short crack lengths, fracture has been followed in the Scanner Electronic Microscope (SEM) with a tensile stage. A Single Edge Notched Tension (SENT) specimen was used. Crack length and applied load during the crack growth were measured. These results have then been used to calculate fracture strength using a linear elastic fracture mechanics and a strip yield model. The results are discussed in general and in particular regarding the importance of process region modelling