This document discusses next generation sequencing (NGS) and its applications in preimplantation genetic diagnosis (PGD). It describes how NGS can simultaneously detect chromosome abnormalities and gene defects in single cells. Studies show NGS has the same accuracy as array comparative genomic hybridization for detecting aneuploidy, and can also detect mutations. NGS has been successfully used to analyze blastocysts and single cells, identifying euploid and aneuploid embryos as well as specific gene mutations. This makes NGS useful for PGD to evaluate chromosome number and identify genetic disorders in embryos prior to implantation.