The study will be conducted in 100 women with recurrent implantation failure The inclusion criteria will be, at least three previous failed IVF attempts where at least 8 good embryos were transferred, women less than 40 years old, absence of systemic diseases. These women will undergo IVF cycle and they will randomly divided in two groups: one (50 women) will be treated with subcutaneous G-CSF 60 micrograms/day from the day of transfer to the day of β-hCG test, and if it will be positive the treatment will be continued for other 40 days; the group of control will be treated with subcutaneous saline solution infusion in the same way of the study group. Primary outcomes will be considered: pregnancy rate and the of β-hCG levels at 14/21/28 and 35 days after embryo transfer.