<p>The inclusion of health-related quality of life (HRQoL) impacts on informal carers in health technology assessments (HTAs) is lacking due, primarily, to a deficiency in evidence and methodological issues on how informal carer HRQoL is captured and incorporated into economic models. These issues are magnified in areas of significant burden, such as caring for children and adolescents with rare, progressive, life-limiting conditions. In this commentary we outline key challenges in measuring, and incorporating in HTA submissions, informal carer HRQoL data in rare, progressive, paediatric, life-limiting conditions and identify future research priorities in this space. We argue that: (i) a generic model of carer HRQoL is likely inadequate to characterise the HRQoL impacts in this population; (ii) the underlying evidence-base is underdeveloped, including understanding commonalities across conditions, impact beyond the primary carer, and differences over time; and (iii) methodological challenges in modelling informal carer HRQoL in cost-effectiveness analysis are inhibiting progress. A research agenda is proposed that addresses these challenges by focusing first on in-depth qualitative research to develop an appropriate, content valid ‘disease-group-specific’ model for understanding informal carer HRQoL in rare, progressive, paediatric, life-limiting conditions. This model can be used to inform the appropriate measurement of carer HRQoL in this population, which, alongside methodological research on addressing modelling challenges, can help to facilitate the recommended inclusion of informal carer HRQoL data in HTA submissions for children and adolescents living with rare, progressive, life-limiting conditions.</p>