The aim of this study is to performed a randomized controlled trial to evaluate the usefulness of preimplantation genetic diagnosis (PGD) in patients with repetitive implantation failure. Patients will be prospectively randomized in two groups: standard IVF with blastocyst transfer on day-5 and transfer day-5 after PGD for aneuploidy screening for chromosomes 13, 15, 16, 18, 21, 22, X and Y. The end points of the study are: Cancellation rate; implantation rate and ongoing implantation rate. Inclusion criteria are: patients with ≥2 previous IVF failure without clinical or biochemical pregnancy with transfer of at least 2 good quality embryos per transfer. Exclusion criteria will be uterine abnormalities , abnormal karyotypes, abnormal result in thrombophilia screening and low responder patients (less than 4 expected oocytes).