An original study of peelback of cellulosic fibres spun using the N-methylmorpholine N-oxide (NMMO) process was performed. 13 micrometre diameter fibres were peeled under a microscope. Due to the high orientation of the material, the rupture could propagate in the centre of the fibres. Fibres presenting very different Fibrillability Index (FI = 0 or FI = 5) and hydration (swollen in water or freezedried) were studied. The resulting surfaces were analysed using Scanning Electron Microscopy (SEM). They showed the original formation of regularly spaced ribs corresponding to tearing of a homogeneous oriented material for the non fibrillable fibres. The structure of fibrillable fibres appeared through the creation of fibrils. Measurements of the energy release rate were performed with a set of each kind of fibres. Low values of this energy were obtained, corresponding to the formation of small ribs, due to the high orientation of the cellulose molecules. The energy values can be increased by the occurence of fibrils in the case of fibrillable fibres.