A micropile is a small diameter “cast-in-situ" pile which was initially used to repair historic buildings. In this paper, a numerical analysis was conducted on the performance of micropiled rafts under pure lateral loading using the finite element modelling. The FEM was calibrated against full scale lateral and axial field tests. Numerous cases were analyzed to investigate the lateral performance of micropiled raft on soft clay soil underlain by a layer of dense sand. The factors that may affect its performance were considered such as: the micropiles spacing, the undrained shear strength and thickness of upper clayey soil layer. The lateral load response of the micropiled raft was assessed. Moreover, the variation of lateral load capacity of single free head micropile with the clay cohesion was evaluated. Then, the effect of the micropiles spacing on the group efficiency was studied. The group effect was found to be insignificant for spacing to diameter ratio larger than 2.31.