BackgroundPhysical frailty is a prevalent syndrome in older adults that increases vulnerability for a range of adverse outcomes including increased dependency and death. Caregivers of older adults experience significant physical, emotional, and financial burden, which is associated with poor physical and mental health. While it is known that care recipients’ dementia is associated with burden, the literature regarding the impact of physical frailty on burden has yet to be synthesized. We conducted a systematic review to assess the state of the evidence regarding the relationship between these two prominent concepts in the geriatric literature.MethodWe used a structured search of databases to identify original English-language articles. Two researchers screened the titles and abstracts of all 1202 retrieved studies and then full-text versions of 265 retained studies. Screening was based on a priori inclusion criteria, which included discussion of physical frailty, caregiver burden, and a population of community-dwelling older adults without dementia. Nine included papers underwent data abstraction and critical appraisal using the Cochrane Risk of Bias Tool or the Newcastle-Ottawa Scale (for randomized controlled trials or cross-sectional studies, respectively). Heterogeneity of the included studies precluded meta-analysis.ResultsFive publications had the same author and drew from the same population; these were treated as a single study. Three of our studies were of limited value since they did not include a validated measure of frailty. While caregivers of frail older adults experience burden, the scarce available evidence and lack of studies comparing this population with normative values does not allow conclusions to be drawn about the strength or nature of the relationship. Judging from excluded studies, the term “frailty” is often used without reference to a clear definition or is treated as synonymous with functional impairment or advanced age.ConclusionsOur review suggests that caregivers of frail older adults experience burden and that the degree of burden may differ from that of other caregiver populations. The limited evidence does not allow conclusions to be drawn or to inform clinical practice. Further research is needed, given the salience of physical frailty and burden.Systematic review registrationPROSPERO CRD42015019198Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-017-0447-1) contains supplementary material, which is available to authorized users.