In a previous study the concept "patient involvement" was found to be strongly predictive of therapy outcome. On the basis of a questionnaire concerning patients' background and motivation, 82 patients were interviewed before treatment. To cover the concept "patient involvement" 16 variables were considered as relevant measures. In a factor analysis four factors accounted for 90% of the common variance. The factors were interpreted in terms of: initial attitudes, attendance, self-confidence and teeth-mindedness.