Recent studies have indicated increased imprinting defects in children born after assisted reproductive technology (ART). The developmental mechanisms are unknown but the Beckwith-Wiedermann syndrome (BWS) and Angelman syndrome (AS) are recognized as imprinting aberration syndromes related to ART. It is also likely that another imprinting aberration syndrome, the Silver-Russell syndrome (SRS), is related to ART. Consideration about the genetic risk of ART is an important matter, and we must examine the association of ART with the occurrence of abnormal imprinting.