Aim: To understand family caregiver involvement in delirium prevention care for older adults hospitalized for orthopedic surgery hospitals and family caregiver integration by nurses.; Design: Multiple-case study.; Methods: The model of Care Partner Engagement was selected as theoretical framework. Eight cases will comprise an older adult hospitalized a family caregiver and a ward nurse. They will be recruited with a non-probability sampling on two orthopedic surgery wards in two hospitals. Semi-structured interviews with participants will be audiotaped. Sociodemographic data will be collected. These data, researcher field notes and interview transcripts will be subjected to within- and across-case thematic analysis. Regional ethics committee approved the study protocol in August 2018.; Discussion: The study will allow surgical nursing teams to gain a better understanding of the issues and possibilities regarding family caregiver integration in delirium prevention care for older adults.; Impact: Integration of family caregivers in care to prevent older adults' delirium is a challenge for nurses. In practice, this study will allow to gain a better understanding of the integration of family caregivers in care to prevent older adults' delirium, the factors that influence it and the ways to improve it. In research, results will be used to develop an intervention whose aim would be a better integration of family caregivers into delirium prevention care that can be tested in the future.