What is original about ART (Assisted Reproductive Technology) is that it is a medical treatment that has a new goal, namely procreation. It is now no longer necessary to have sexual intercourse in order to conceive a child. This is deeply challenging to what until now was thought of as being something intangible and somehow divinely ordained. This paper is based on a ten-month sociological survey in a French hospital, during which 138 medical appointments were observed and 50 in-depth interviews conducted with patients and medical staff. The purpose was firstly to look at the place given to religious variables in courses of ART, and, secondly, to understand the motivations of the believers who are transgressing religious taboos. How do they justify their choice? What kind of compromise do they make? Generally, this paper seeks to understand the ethical (or moral) standards professed by the individuals involved. The “desire to have children” is somehow at the center of these norms.