The permeability of bovine articular cartilage was measured in an apparatus designed to permit this measurement while the fluid pressure gradient across the cartilage and the axial compressive strain applied to the cartilage were varied independently. For all of the pressure gradients tested the permeability of the cartilage decreased as the compressive strain increased. From previous work, it was postulated that joint lubrication is accomplished first by fluid exudation into the joint space. both at the leading edge of the moving contact area and between portions of the opposing cartilaginous surfaces, and second by imbibition of the expelled fluid back into the cartilage toward the trailing edge of the contact area caused by the "elastic" recovery of the tissue. The present work extends this model to include the condition that the permeability of cartilage is dependent on the extent to which it is deformed.