The influence of polystyrene beads (80 mu m) and nylon fibres on the water permeability of bleached kraft wood pulp fibre pads was measured and the results were regressed to the Kozeny-Carman equation. SEM micrographs of pad cross sections showed that the beads, which were uniformly distributed, had little effect on pad structure whereas the long rigid nylon fibres made the pads more difficult to compress. The pad specific surface areas and swollen volumes were linear functions of the content of beads or nylon fibres. This suggests that the fibre pad permeability characteristics could be adequately modeled from the linear superposition of geometric properties of the pad constituents.