Objective: To study the motivations underlying IVF-ET participants' choice to donate or destroy their supernumerary embryos. Design: Couples' opinions are studied through a questionnaire and a psychological interview. Participants: Two hundred couples about to undergo NF-ET. Setting: The fertility unit of an academic hospital. Main Outcome Measures: Couples' choice for supernumerary embryos' destiny; opinions on embryo status, on importance of genetic lineage in the filial bonding, on gamete donation, and on multiple pregnancy risk. Results: Donation is the most frequent choice but destruction is tolerated by almost all the couples (92%). Couples considering the embryo as a child choose destruction as frequently as donation but refuse experimentation on the embryo. Donation is highest among couples who stress education more than genetic lineage in parental bonding. This is confirmed by the choice of the couples requiring donor gametes. Couples express differing attitudes toward risks of twins and risks of triplets: twins are much more desired than triplets, which are frequently refused. Conclusions: Couples' opinions on the respective importance of genetic lineage and education in defining parental bonding are more determinant in their decision to destroy or to donate their supernumerary embryos than their opinions on the in vitro embryo status, which only determines their attitude toward experimentation.