The transmissibility characteristics of oil-lubricated porous journal bearings are analytically determined for a rigid rotor mounted in both the horizontal and the vertical positions. The bearing model used in this investigation is the short-bearing approximation with isothermal conditions and a 180-degree cavitated film. All data presented are for a range of unbalances that may commonly be encountered in practice. These data show that operating conditions exist for which porous journal bearings exhibit transmissibility characteristics that are superior to those of corresponding solid journal bearings. All data presented for porous bearings were obtained by using a bearing with a wall thickness-to-length ratio of 0.2.