The advent of assisted reproductive technology (ART) has taught us a great deal about human fertilization patterns. Thirty years of experience with IVF and cultivation of early embryos has provided a unique view into the mechanisms of normal and aberrant human fertilization. Here we review the different types of triploidy following conventional in vitro fertilization and intracytoplasmic sperm injection, as well as the mechanisms giving rise to digynic and dispermic fertilization. Additionally, the role of the centrosome in triploidy, the genetic analysis of triploid embryos and the potential for therapeutic enucleation are explored. Lastly, we review our own clinical experience with human fertilization patterns following > 20,000 treatment cycles of assisted reproduction.