The goal of this study was to gain a greater understanding of the changes in the mechanical properties of spring wood fibres during the consolidation of the web. It was found that the elastic modulus of freely dried fibres E is essentially tripled by any axial load applied during drying. Their tensile strength t is increased and their stretch of is decreased in proportion to the loads applied during drying up a twofold change. The elastic modulus measured at 90°to the fibre axis E1, was found to be about 0.1E. These fibre properties are of paramount importance to the stress/strain properties of paper, which are described quantitatively in terms of the fibre properties and sheet structure in our second contribution to this symposium.