In vitro fertilization (IVF) has made it possible for an increase in the knowledge of the potential of sperms to fertilize. IVF has confirmed that the classical parameters accepted in assessing spermograms does not constitute a sure way of predicting whether a subject is fertile or sterile. It is necessary to increase and redefine these data with new parameters. New techniques have been developed during the last few years to assess the functional quality of sperm and their efficiency so that in future they can be correlated with sperm fertility at least within the context of in vitro fertilization. The precise mechanisms that are responsible for infertility are still badly understood; so that it will be valuable to study at the cellular level interactions between spermatozoa and oocytes. This article describes some of the elements that could make it possible to assess sperm fertilizing capacity.