#### Summary points Preimplantation genetic (PG) testing is the practice of obtaining a cellular biopsy sample from a developing human oocyte or embryo, acquired via a cycle of in vitro fertilisation (IVF); evaluating the genetic composition of this sample; and using this information to determine which embryos will be optimal for subsequent uterine transfer. PG testing was first described in 1990 when the sex of cleavage stage embryos in two couples, both with X linked diseases, was determined.1 The applications and use of various types of PG testing have continued to increase. However, the benefits and limitations of PG testing, both in popular culture and the medical community, are often misunderstood. This article reviews the technologies available in PG testing, and discusses the risks, ethical considerations, appropriateness, and controversy surrounding its use in different clinical situations. #### Sources and selection criteria The information sources used to compile this …