Aneuploidy screening (AS) of oocytes and embryos in connection with infertility treatment is increasingly used. The purpose of AS is multiple: 1) to increase the implantation rate, 2) to reduce the risk of spontaneous abortion, 3) to reduce the frequency of multiple pregnancies and 4) to increase the chance of having a chromosomal normal child. Many morphological normal embryos are aneuploid and the aneuploidy rate is positively correlated to the woman’s age. As many couples seeking IVF treatment are above 35 years, especially this group of patients could potentially benefit from AS. Removal of blastomers from embryos or evaluating one or two of the polar bodies from the oocytes are both techniques used for AS. However, they are both technical difficult and expensive to perform, and AS is overall only used on a very limited number of cases. The polar bodies are considered to have no biological role during subsequent embryonic development. Although chromosomal errors arising during the second meiotic division in the oocyte and/or deriving from the spermatozoa will not be detected by analysis of the first polar body it can potentially reduce the number of chromosomal abnormal embryos replaced substantially. Diagnosis on the first polar body is an attractive solution since removal can be performed already on the day of oocyte retrieval, it does not affect the oocyte per se and leaves one or two days for analysis prior to embryo transfer. However, a widespread use of AS awaits large prospective randomized trials to investigate the real effect of AS.