ABSTRACT Objectives: Carer burden is common in younger-onset dementia (YOD), often due to the difficulty of navigating services often designed for older people with dementia. Compared to Alzheimer’s disease (AD), the burden is reported to be higher in behavioral variant frontotemporal dementia (bvFTD). However, there is little literature comparing carer burden specifically in YOD. This study hypothesized that carer burden in bvFTD would be higher than in AD. Design: Retrospective cross-sectional study. Setting: Tertiary neuropsychiatry service in Victoria, Australia. Participants: Patient-carer dyads with YOD. Measurements: We collected patient data, including behaviors using the Cambridge Behavioral Inventory-Revised (CBI-R). Carer burden was rated using the Zarit Burden Inventory-short version (ZBI-12). Descriptive statistics and Mann-Whitney U tests were used to analyze the data. Results: Carers reported high burden (ZBI-12 mean score = 17.2, SD = 10.5), with no significant difference in burden between younger-onset AD and bvFTD. CBI-R stereotypic and motor behaviors, CBI-R everyday skills, and total NUCOG scores differed between the two groups. There was no significant difference in the rest of the CBI-R subcategories, including the behavior-related domains. Conclusion: Carers of YOD face high burden and are managing significant challenging behaviors. We found no difference in carer burden between younger-onset AD and bvFTD. This could be due to similarities in the two subtypes in terms of abnormal behavior, motivation, and self-care as measured on CBI-R, contrary to previous literature. Clinicians should screen for carer burden and associated factors including behavioral symptoms in YOD syndromes, as they may contribute to carer burden regardless of the type.