BACKGROUND:Australia is one of many nations struggling with the challenges of delivering quality primary health care (PHC) to increasing numbers of refugees. The OPTIMISE project represents a collaboration between 12 organisations to generate a model of integrated refugee PHC suitable for uptake throughout Australia. This paper describes the methodology of one component; an outreach practice facilitation intervention, directed towards improving the quality of PHC received by refugees in Australian general practices. METHODS:Our mixed methods study will use a cluster stepped wedge randomised controlled trial design set in 3 urban regions of high refugee resettlement in Australia. The intervention was build upon regional partnerships of policy advisors, clinicians, academics and health service managers. Following a regional needs assessment, the partnerships reached consensus on four core areas for intervention in general practice (GP): recording of refugee status; using interpreters; conducting comprehensive health assessments; and referring to refugee specialised services. Refugee health staff trained in outreach practice facilitation techniques will work with GP clinics to modify practice routines relating to the four core areas. 36 general practice clinics with no prior involvement in a refugee health focused practice facilitation will be randomly allocated into early and late intervention groups. The primary outcome will be changes in number of claims for Medical Benefit Service reimbursed comprehensive health assessments among patients identified as being from a refugee background. Changes in practice performance for this and 3 secondary outcomes will be evaluated using multilevel mixed effects models. Baseline data collection will comprise (i) pre-intervention provider survey; (ii) two surveys documenting each practices' structure and approaches to delivery of care to refugees. De-identified medical record data will be collected at baseline, at the end of the intervention and 6 and 12 months following completion. DISCUSSION:OPTIMISE will test whether a regionally oriented practice facilitation initiative can improve the quality of PHC delivered to refugees. Findings have the potential to influence policy and practice in broader primary care settings. TRIAL REGISTRATION:Australian New Zealand Clinical Trials Registry, ACTRN12618001970235 , 05/12/2018, Retrospectively registered. Protocol Version 1, 21/08/2017.