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Trophectoderm (TE) biopsy and DNA microarray have become the new technologies for preimplantation genetic diagnosis in humans.A previous study comparing the performance of different platforms for DNA microarray found that the oligonucleotide (oligo) microarray platform containing 385K isothermal probes had the best performance when evaluating dosage sensitivity, precision, specificity, sensitivity and copy number variations border definition.Although oligo microarray platform has been used in some research fields and clinics, it has not been used for aneuploidy screening in human embryos.Objective The present study was designed to use this new microarray platform for preimplantation genetic screening in the human.Biopsied cells from either TE or inner cell mass (ICM) were processed for microarray to examine the errors in 23 pairs of chromosomes and the consistency between TE and ICM.Methods A total of 383 blastocysts from 72 infertility patients with either advanced maternal age or with previous miscarriage were analyzed after biopsy and microarray.Results Microarray of TE and ICM cells in the same blastocysts revealed that high proportions (69.2%) of aneuploid blastocysts were mosaic including aneuploid TE and euploid ICM, inconsistent anomalies between ICM and TE, or euploid TE cells and aneuploid ICM in the same blastocyst.Euploid blastocysts were transferred to patients and clinical pregnancy and implantation rates were measured.We found that most (58.1%) of the blastocysts had chromosomal abnormalities that included single or multiple gains and/or losses of chromosome(s), partial chromosome deletions and/or duplications in both euploid and aneuploid embryos.Transfer of normal euploid blastocysts in 34 cycles resulted in 58.8% clinical pregnancy and 54.4% implantation rates.Conclusion The present study indicates that oligo rnicroarray conducted with a higher resolution and a greater number of probes is able to detect not only aneuploidy, but also minor chromosomal abnormalities in human embryos.These results indicate that high proportions of human blastoeysts produced in in vitro from women of advanced maternal age are aneuploid and mosaic.Errors can occur in any of the 23 pairs of chromosomes in human blastocysts.Preimplantation genetic screening of the aneuploidy by DNA microarray is an advanced technology used to select embryos for transfer and improved embryo implantation can be obtained after transfer of the screened normal embryos.