Regenerated cellulose fibres of different origin were tested in tension and by means of nanoindentation. Their degree of molecular orientation was characterised with birefringence measurements. An empirical relationship was set up between the degree of orientation expressed by birefringence and the modulus of elasticity parallel to the fibre direction, and the ratio between this modulus and the modulus transverse to the fibre direction, respectively. (c) 2007 Elsevier Ltd. All rights reserved.