This chapter provides an outline of prenatal screening followed by an overall coverage of common indications for prenatal diagnosis and the associated risks and benefits. In recent years, the scope of prenatal diagnosis has expanded greatly with the development of screening tests like maternal serum biochemical screening and fetal nuchal translucency. Most women in the developed countries are offered some form of prenatal screening in pregnancy that may subsequently lead to a specific diagnostic test. Prenatal screening is becoming close to being a routine part of antenatal care. The main aim of prenatal screening is to identify “high risk” pregnancy. To date, there are few prenatal treatment modalities available for specific disorder and the general common goal of screening at present is to reduce the number of babies with disabilities born through “thera-peutic abortions”. Prenatal diagnostic tests are usually invasive and carry a small risk of fetal loss. There is a definite distinction between prenatal screening and prenatal diagnosis. The former is generally noninvasive whilst the latter usually entails invasive procedure that carries a risk of fetal loss. Routine anomaly scanning at between 18 and 20 weeks of gestation. Prenatal diagnostic tests are—ultrasound, chorionic villi sampling, amniocentesis, cordocentesis, fetal blood sampling.