OBJECTIVES: Interest in the measurement of health-related quality of life (HRQoL) in children and adolescents has been increasing, and appropriate instruments are required for this target group. This article focuses on the EQ-5D-Y instrument, presenting an overview of its characteristics, development, and current use, and includes a discussion of methodological and conceptual issues related to the valuation of child health and the development of an EQ-5D-Y value set. METHODS: This article brings together the experiences of the research team that developed and validated the EQ-5D-Y, supplemented by information derived from EQ-5D-Y study registrations on the EuroQol Group's website. RESULTS: EQ-5D-Y is a child-specific and age-appropriate measure of HRQoL. Study registration data show that the instrument's use has steadily increased since its first publication. It has been used in various types of studies and in different disease areas. Currently there is no value set for EQ-5D-Y, and so its use in cost-utility analysis (CUA) is limited. There are methodological and conceptual issues that affect the design of valuation studies for child health. Issues that are discussed include the need for separate value sets for children and adolescents, the choice of appropriate reference samples and valuation techniques, and the framing of the tasks. CONCLUSIONS: Research on EQ-5D-Y and its use has increased in the last years. Further research is required to clarify methodological issues regarding health state valuation in children and adolescents. This will support the development of a value set for EQ-5D-Y and the use of EQ-5D-Y in CUA.