This study investigated the minimally required feedback elements of a computer-tailored dietary fat reduction intervention to be effective in improving fat intake. In all 588 Healthy Dutch adults were randomly allocated to one of four conditions in an randomized controlled trial: (i) feedback on dietary fat intake [personal feedback (P feedback)], (ii) P feedback and feedback on one's own behavior relative to that of peers [personal-normative feedback (PN feedback)], (iii) PN feedback and practical suggestions on how to change fat intake [personal-normative-action feedback (PNA feedback)] and (iv) generic information. Data on fat intake, awareness of one's own fat intake and intention to change were collected 1 and 6 months post-intervention. Between-group differences were tested with analysis of variance. Among respondents with high fat intakes at baseline (risk consumers) and those who underestimated their fat intake at baseline (underestimators), differences in awareness and (saturated) fat intake were found between the generic and PNA feedback conditions. Compared with generic information P feedback was more effective in changing awareness and intention among the underestimators, and PN feedback was more effective in changing intention among both risk consumers and underestimators. In conclusion, the combination of personal, normative and action feedback is required for inducing change in fat intake and improving awareness of fat intake. AD - 1Department of Public Health, Erasmus University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, The Netherlands.