The author deals with the ethical problems arising from the techniques of prenatal diagnosis and fetal therapy. With regard to the use of prenatal diagnostic response, he underlines the frequent connection between the unfortunate response and the voluntary termination of pregnancy; with regard to this, he reports the various positions which can be found in the literature on ethics. In the light of Catholic ethics, the author affirms that prenatal diagnosis is only acceptable when it respects the life and integrity of the embryo and the human fetus and is directed towards its safeguarding or healing. The moment and form of the communication of the response is also considered. Finally, some guidelines to justify conditions for fetal therapy intervention are pointed out.