Total hip replacement is one of the most common techniques in orthopaedic surgery, and one of the most important surgical advances of the last XX century. Normally, implant is fixed to bone by means of a polymer material known as bone cement, building an interface between implant and bone regions. Microscopically, two interfaces can be distinguished, namely, bone-cement and implant-cement interfaces. One of the main causes of failure is implant loosening due to fatigue of one of the two microscopic interfaces. In this work, a micromechanical analysis of bone-cement interface under cyclic forces is introduced. Both bone and cement are considered using different models based on fatigue damage over a statistically representative volume element (RVE) of the microstructure. This technique allows to homogenize mechanical stresses of the RVE yielding the effective macroscopic behavior of the bone-cement interface, avoiding experimental fitting case to case, once the interface geometry and mechanical characterization of the involved phases are known.