We present preliminary studies of the rheological properties and dispersion stability of MR fluids as a function of particle shape by comparing fluids made with uniform nickel spheres to those employing nickel microrods suspended in silicon oil. The rods were fabricated using template-hased electrodeposition having diameters in the range 300 ± 30 nm and lengths in the range of 5 - 25 μm. The properties of these rods were compared to commercial nickel carbonyl spheres (1-10 μm dia.). Qualitatively, the off-state (field off) viscosity of fluids containing only rods was found to be substantially greater than those that contain only spherical particles. Rheological measurements of the on-state viscosities were conducted using a custom rheometer equipped with an electromagnet capable of magnetic fields up to 0.6 T. Placed in this field, we observed yield stresses of 1.88 ± 0.23 and 1.86 ± 0.26 kPa, respectively for 7.6% volumc fraction of pure nickel spheres and rods, respectively. Due to limitations of the testing apparatus, only the on-state properties of these fluids were investigated. For this reason, the yield stress values reported do not account for the difference in off-state viscosity. While the fluids containing spherical nickel particles tended to settle rather quickly (< 20 minutes), those containing only rods remained suspended even after 48 hours.