Laboratory advances in molecular genetics have resulted in numerous clinical applications for DNA analysis. Currently, because of cost, complexity, and resource limitations, DNA analysis is not used routinely for prenatal screening, but rather is targeted towards families at risk for an inherited condition. This article discusses the types of DNA analyses that are currently performed, the possible tissue sources of DNA for prenatal diagnosis, and the indications for DNA testing in obstetric practice. Internet addresses for the most up-to-date genetic information on a specific condition are given in this article.