The Leuven Family Questionnaire is a new instrument based upon the structural family theory of Minuchin. It measures the perception of conflict, cohesion and disorganisation in the family. The scales proved to be internally consistent and stabile on a short-term basis, and showed sufficient convergent validity. The usefulness of this instrument for comparing clinical groups on the one hand and the opinions of members of the same family on the other is demonstrated. A case study is presented in which the results of all family members and the discrepancies between them were used to develop a working hypothesis at the beginning of therapy.