Introduction The development of incubators with built-in time-lapse technology has enabled continuous non-invasive monitoring of embryo development from fertilization to blastocyst stage and the possibility of appraising the precise timing of embryonic cell divisions. Many studies have tried to connect, more or less conclusively, embryo development, timing of mitotic divisions, embryo viability, aneuploidy and implantation. However, to the best of our knowledge, morphokinetics of euploid embryos have not been explored regarding which time points are critical for their implantation. Material and Methods This observational study was based on 143 patients (mean age: 35.07) applying for preimplantation genetic screening (PGS) due to advanced maternal age (>37) or a history of abnormal fetal karyotype. Patients with structural abnormalities were not included in the analysis. Cases included in the analysis had at least two euploid embryos and all embryos were cultured in a time-lapse incubator (EmbryoScope™). Good or top-quality blastocysts (at least 4BB) were biopsied and analyzed either by next generation sequencing (NGS) (PGM platform, ThermoFisher) or by array Comparative Genomic Hybridization (aCGH, Illumina). Embryo morphokinetics of 57 patients with a negative outcome were compared to 86 patients with an ongoing pregnancy. Results Morphokinetic variables for all cleavage events up to the expanded blastocyst stage were annotated. All relevant events (fertilization, cleavages, morula and blastocyst formation) were checked on a daily basis, and time of cleavage to two-cell embryo (t2) and subsequent divisions t3, t4, t5, t6, t7, t8 and t9+ were recorded in the EmbryoViewer® workstation. The time of all mitotic events was expressed as hours post-ICSI. Error! Not a valid link.The kinetics of euploid embryos was evaluated according to their pregnancy outcome. Implanted euploid embryos were faster for each embryonic event or cleavage time annotated. When median values were compared, a time difference of 0.3-3.28h was found between implanted and non-implanted euploid embryos, statistically significant differences being found for pronuclei appearance (tPNa) (p=0.0065) and the time to achieve 9 cells (t9) (p=0.0132). Conclusions Although many algorithms regarding the deselection of aneuploid embryos have been published, none have focused on the selection of euploid embryos. Our study showed that, overall, implanted euploid embryos were faster for each embryonic event or cleavage time annotated. Additionally, the first event annotated, the pronuclei appearance and last cleavage (t9) are significantly different in implanted and non-implanted euploid embryos. These morphokinetic criteria may be used to prioritize euploid embryos for transfer.