There are many papers on the experimental investigations of porous bearings under static loads but there is no paper on the experimental investigations under dynamic loads. In the present paper, the results of experimental investigation of porous bearings under vertical sinusoidally fluctuating loads are presented. The friction force was measured under various conditions of fluctuating load/steady load ratio, journal frequency and load frequency. The investigations were carried out in the hydrodynamic lubrication regime in a specially designed and fabricated test rig. It was found that at any given rpm, as the fluctuating specific load/steady specific load ratio, Pf/Ps, increases, the mean coefficient of friction μm increases. It was also found that the mean coefficient of friction is not affected by the load frequency even when the load frequency is half of the journal frequency. © 1998 Elsevier Science Ltd. All rights reserved.