AIM: The objective of this study was to explore family caregivers' experiences with the impact of Huntington's disease (HD) on the family structure and roles in the family. METHODOLOGY: We interviewed 15 family caregivers in families affected by HD, based on a semi-structured interview guide. The participants were recruited through hospital departments and a lay organisation for HD in Norway. Data from the interviews were analysed with systematic text condensation. RESULTS: Huntington's disease could have a substantial impact on the family system, the shape of roles among family members and the hierarchical order between spouses, partners, and parents and children. The relationship between spouses and partners changed during the course of the disease. A reciprocal relationship was difficult to maintain, as the role as carer overshadowed other roles. Children of an affected parent could compensate for impairments by taking on adult responsibilities, and in some families, a child had the role as main caregiver. The increasing need for care could cause conflicts between the role as family member and family caregiver. The burden of care within the family could fragment and isolate the family. CONCLUSIONS: Huntington's disease has a major impact on family systems. Caregiver roles are shaped by impairments in the affected family member and corresponding dynamic adoption and change in roles within the family. Making assessments of the family structure and roles, professionals may understand more about how to care for and support individuals in their role as family members and caregivers in different stages of the disease and family life cycle.