The preferences of informal carers are important to capture for healthcare decision making. This paper discusses how these preferences relate to the economic evaluation of health and care interventions. Three main issues are highlighted. First, there is a need to consider carer impact routinely in economic evaluations. Second, more debate is required around the ethical issues stemming from the inclusion of interdependent preferences in healthcare decision making. Third, there are a number of situations where carer and patient preferences may conflict and practical ways of representing and handling these conflicts would be useful.