In this contribution, we consider detection of 47,XXY by a variety of available methods. These include traditional invasive procedures, screening with maternal serum analytes and fetal ultrasound, and most recently cell-free fetal DNA. Since its introduction in the late 1960s, prenatal genetic diagnosis has evolved greatly. Serendipitious detection of 47,XXY was not infrequent when prenatal genetic diagnosis routinely involved testing by the invasive procedures CVS and amniocentesis. In 2013 this is much less common and relatively few pregnancies in the U.S. and Europe are tested without prior screening protocols, traditionally maternal serum analyte and fetal ultrasound (NT). These protocols are not designed to identify 47,XXY or other X-chromosome aneuploides and with screening by analysis of cell-free DNA in maternal blood, this situation may or may not be altered. Increased numbers of cases could be detected if intake increases and vendors offer information on 47,XXY. A further consideration is that ability of array CGH to detect microdeletions or microduplications below resolution of a karyotype could make return to direct testing using an invasive procedure attractive. © 2013 Wiley Periodicals, Inc.