Implantation failure remains one of the major factors limiting success in IVF treatment. It was postulated that the local injury to endometrium induces secretions of cytokines and growth factors such as leukemia inhibitory factor, interleukin-11, and heparin-binding EGF-like growth factor which enhance decidualisation and facilitate implantation. It may also up-regulate the gene expressions related to endometrial receptivity and optimize the endometrial development. In stimulated cycles, local injury to the proliferative endometrium has been postulated to delay endometrial development thereby inducing synchronicity between endometrium and embryo stage and facilitate implantation (Zhou et al, 2008; Almog et al, 2010; Gnainsky et al, 2010) The aim of the study is to determine whether endometrial injury by endometrial biopsy in mid-secretory phase of the preceding cycle would improve the on-going pregnancy rate in subfertile women undergoing IVF treatment.