Lattice Boltzmann method is used to investigate sedimentation of a single fiber in a Newtonian fluid. The effects of the aspect ratio of a fiber are carefully examined. The computational results show that the stable orientation of a single fiber is the horizontal direction. The terminal Reynolds number increases as the aspect ratio increases, and basically remains invariable when the aspect ratio is high enough. The lateral drift of the fiber is more apparent at higher aspect ratios and the orientation of the fiber at which the lateral drifting velocity reaches the maximal is not sensitive to the value of the aspect ratio. When the aspect ratio is around 2.8, the fiber rotates fastest from the vertical location to the horizontal. Some of the results are compared with the experimental data and good agreements are found. (C) 2003 Elsevier Ltd. All rights reserved.