Apolar organic suspensions of rodlike cellulose whiskers modified by a surfactant are investigated by small angle neutron scattering. Guinier and Porod analyses are performed to characterize the increase of cross-sectional radius of gyration observed between organic and aqueous suspensions of whiskers. In addition, a comparison with theoretical curves for fibers with homogeneous rectangular cross sections finally leads to typical cross-sectional dimensions of ca. 120 x 210 Angstrom(2) for the modified whiskers in organic solutions while those in water have 88 x 180 Angstrom(2) Sizes. It is concluded that the modified whiskers are coated with a surfactant layer of 15 A thickness in a rather folded conformation.