Background: Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. In Ireland, a dearth of research on TBI means that we neither know the number of people affected by this injury, nor have the information required to improve neuro-rehabilitation services. Aims: This is the protocol for a study that will examine pathways through rehabilitation for survivors of TBI in the Republic of Ireland. The experiences of family members providing care or support to a person with TBI will also be explored. Additionally, the study will estimate the incidence and prevalence of TBI in Ireland. Epidemiological data and information on how people with TBI access rehabilitation and health services will support advocacy efforts towards the redevelopment of neuro-rehabilitation services. Methods: The research is a mixed method, observational cohort study design. Participants with moderate to severe TBI will be recruited through two brain injury service providers, two acute hospitals that provide neurosurgical services, and the National Rehabilitation Hospital. Questionnaires will be administered to participants with TBI on two separate occasions, six months apart, and to family members providing care or support to an individual with TBI, on one occasion. Data from the medical records of participants will be abstracted to capture key information about their brain injury. TBI survivor participants’ use of health care will be followed prospectively for six months. Expected outcomes: The study will outline participants’ pathways through rehabilitation in Ireland, to understand how rehabilitation services are accessed, and the barriers to accessing these services. The incidence and prevalence of TBI in Ireland will be estimated. Experiences of family members providing care or support to an individual with TBI will be detailed. The outcomes of the study will support ongoing efforts to improve care for TBI survivors in Ireland and to redevelop neuro-rehabilitation services.