A trace amount of vapor-grown carbon fibers (VGCFs) were dispersed in polydimethylsiloxane (0.097 Pa s) by mechanical stirring. A magnetic field (0.23 T) was applied to the dispersion while in situ optical microscope observation was performed. The alignment rate was determined through analysis of the VGCF orientation. Using this suspension method, the diamagnetic anisotropic susceptibility of VGCF was estimated to be 3.11 x 10(-4) (-). From this value, the alignment time of VGCFs was estimated as a function of viscosity or magnetic field. The anisotropic susceptibility of VGCFs was compared with those of conventional carbon fibers. (c) 2007 Elsevier B.V. All rights reserved.