This review summarises the current knowledge on preimplantation genetic testing for aneuploidy (PGT-A). Selection and transfer of euploid embryos aim to improve live birth rate (LBR) per embryo transfer, but fluorescence in situ hybridisation-based PGT-A and biopsy of cleavage stage embryos in the 2000s was a disappointment, as studies revealed a reduced LBR. Today, PGT-A includes comprehensive chromosome screening primarily of blastocyst biopsies. The benefit of PGT-A is highly debated: some suggest improved treatment outcome, while others claim, that the procedure is not cost-effective.