In conference interpreting, "relay" is used when one or several members of a team do not cover all the working languages. In spite of strong recommendations to avoid the systematic use of relay, the growth of conference languages has been such that relay has remained and grown along with the number of languages used for international meetings. Therefore, interpretation students must learn how to work in this mode. The authors of this article propose to show the constraints of the method as well as its possible advantages in training. Sample renditions are analyzed for variations, literalness, levels of style, snowballing errors and the importance of background knowledge.