A questionnaire survey of judges in charge of family cases, supported by an interview survey of judges, provides an opportunity to find out what judges think about child support guidelines. Although the use of the guidelines is frequent, judges remain critical, opposing its usefulness to the preservation of their discretion. Their criticisms and suggestions for improvement testify to their lack of knowledge of the explanatory document initially associated with the guidelines, which was distributed independently of the guidelines. The use of guidelines does not seem to be related to the existence of claims of an unusual amount or to on the principle under which the parties delimit the scope of the case: few judges set child support outside the range of supply and demand, even when these amounts are below the amount recommended by the guidelines.