Quality of life measurement has become a major topic in pediatric medicine alongside the advances in medical care of children with chronic conditions. In particuar, chronic conditions have been reported to affect family functioning and family well-being. The IOFS (Impact On Family Scale) questionnaire is an instrument measuring health and quality of life which enables quantification of the impact on the family of chronic childhood conditions. This instrument, initially developed by Stein et al. with 33 items and 4 dimensions was progressively reduced to a 15-item questionnaire with one main dimension representing general negative impact on the social and familial systems. To date, validations of cross-cultural adaptations of the IOFS have been performed in different languages: Spanish, Italian, German, Portuguese and Turkish. As this instrument was still not validated in French, we pro- posed to translate, adapt and validate the IOFS questionnaire for clinical and research use in French-speaking populations.