Synovial joints represent the main and most important feature of the human body as they represent the centers of the most essential and basic activity in the humans, which is the motion. During motion synovial joints are subjected to an enormous range of loading conditions ranging from high load with low speed to low load with high speed. Despite of these complicated conditions synovial joints remain efficient for many years which, in turn, bearing out the presence of the effective lubrication system. Starting from the role that are played by the lubrication system in effectiveness and maintenance of the joint this study was initiated, which investigates the lubrication systems that are operative in synovial joint. The goal of this study is to determine the profile of synovial film thickness and the pressure developed in the joint when the hydrodynamic and elastohydrodynamic lubrication theories are operative. The various lubrication theories encountered in engineering that are adopted for synovial joints are discussed and the basic characteristics of each theory are described. This survey covers hydrodynamic, elastohydrodynamic, squeeze-film, weeping and boundary lubrication. The loading conditions and sliding velocity during one gait of the walking cycle was analyzed and generally the cycle is classified into three regions: unloaded region, lightly loaded region and highly loaded region. For each region an assessment of the minimum film thickness has been made. During the unloaded region, the swing phase of the walking cycle, the hydrodynamic lubrication theory was studied at which a mathematical equation that describes the pressure distribution of the synovial fluid (lubricant) was adopted using Martin_s solution. During the lightly loaded region, the weight transfer phase of the walking cycle, the elastohydrodynamic lubrication system was examined in which the finite difference method with a combination of direct-iteration and Newton-Raphson techniques were used to solve the simultaneous system of Reynolds and elasticity equations, under cylindrical line contact and isoviscous condition. The results showed that hydrodynamic action occurs in about 46.3.