In view of insufficient clinical evidence demonstrating the value of AH at the start of our study and in view of the need for higher implantation and LBRs in our ART programme within a series of reimbursed cycles, a prospective randomized controlled trial was performed to evaluate the effect of AH, by modified quarter laser-assisted zona thinning (mQLAZT), in our cryopreservation program. The primary aim was to test the hypothesis that the IR per embryo transferred is higher after transfer of frozen/vitrified-thawed/warmed embryos with thinned ZP after mQLAZT when compared with the transfer of frozen/vitrified-thawed/warmed embryos without mQLAZT.