OBJECTIVES: The aim of this study was to evaluate inter-rater and inter-modality agreement in assessing health status using the Health Utilities Index Mark 3 (HUI3). METHODS: A random sample from a Dutch cohort of 14-year-old Very Low Birth Weight children and their parents were invited to participate in a HUI3 face-to-face (n=150) or telephone interview (n=150). All 300 participants were also sent a HUI3 questionnaire by mail. Response rate was 68%. RESULTS: Inter-rater and inter-modality agreement were high for the physical HUI3 attributes and poor for the psychological attributes. Children and parents reported more dysfunction in the psychological attributes when interviewed than when completing the mailed questionnaire. High agreement on the physical attributes may have resulted from the fact that hardly any dysfunction was reported in these attributes, and poor agreement in the psychological attributes may have been a result of the fact that in these attributes much more dysfunction was reported. CONCLUSIONS: In measuring children’s health status using the HUI3, the results and their interpretation vary with the source of information and the modality of administration. For maximum comparability between studies, written self-report questionnaires seem the preferred option.