The diagnosis of genetic pre-implantation (PGD) is the most recent test amongst the genetic diagnostic techniques. This works analyses its development, medical indications and bio-ethical dilemma that may occur with indiscriminate use. It has been proposed as well that some questions guiding the physicians in the decision making process to implant or not an embryo with some genetic defect. And last, some philosophical issues are also analyzed in pro or against PGD.