Background: The association between caregiver burden and the physical frailty of older adults has been the object of previous studies. The contribution of patients’ dispositional optimism on caregiver burden is a poorly investigated topic. The present study aimed at investigating whether older adults’ multidimensional frailty and optimism might contribute to the burden of their family caregivers. Methods: The Caregiver Burden Inventory was used to measure the care-related burden of caregivers.