A three-dimensional analysis of the human ankle joint is presented to analyse data obtained from gait laboratory tests. The ankle was treated as consisting of two joints, the talocrural (Tc.) and the talocalcaneonavicular (Tcn.), and relevant anatomical dimensions were based upon cadaveric anthropometric data. Seven adult male subjects were studied during the stance phase of normal locomotion. Data was acquired from three orthogonally placed cine cameras and a force platform. Two models were investigated based on force equilibrium; a Mark I model which excluded the posterior tibial and peroneal muscle groups and a Mark II model, which included them. The Mark II model gave the following resultant peak forces expressed as multiples of body weight; Tc. joint force = 3.9; Tcn. joint forces--anterior facet = 2.4, posterior facet = 2.8. The latter model was felt to have good potential in the analytical assessment of ankle pathologies and endoprostheses.