Chromosomal microarray analysis is a technique that identifies chromosomal abnormalities, including submicroscopic abnormalities that are too small to be detected by conventional karyotyping. Like conventional fetal karyotyping, prenatal chromosomal microarray analysis requires direct testing of fetal tissue and thus can be offered only with chorionic villus sampling or amniocentesis. Based on the results of a Eunice Kennedy Shriver National Institute of Child Health and Human Development multicenter trial and of prior studies, prenatal chromosomal microarray analysis is most beneficial when ultrasonographic examination identifies fetal structural anomalies. The potential for complex results and detection of clinically uncertain findings identified by prenatal chromosomal microarray testing can result in substantial patient anxiety. This underscores the critical need for comprehensive patient pretest and posttest genetic counseling from qualified personnel about the benefits, limitations, and results of testing so that patients can make informed decisions. The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine offer background information as well as recommendations regarding the application of chromosomal microarray technology in the prenatal setting.