This report describes the electromechanical potentials measured from within the matrix of human articular cartilage. The potential is increased with increasing load, increasing load rate, and increasing strain concentration. Cartilage is heterogeneous; numerous artefacts are present and must be carefully excluded. The origin of the potential is complex but probably includes such effects as streaming potentials, Donnan equilibrium, dipole orientation of collagen fibers, and alteration in spatial distribution of hydrogen bonds.