Objectives To describe the prevalence and trajectory of family caregivers' post-traumatic stress symptoms during the first year after a patient's admission to the intensive care unit and identify associations between family caregivers' background characteristics, hope and post-traumatic stress symptoms. Research methodology/designs Family caregivers of intensive care unit patients (n = 211) completed questionnaires at patient admission to the intensive care unit and thereafter at 1, 3, 6, and 12 months. Mixed-model analyses were performed. Setting Four intensive care units in a university hospital in Norway. Main outcome measures Impact of Event Scale—Revised and Herth Hope Index. Results On admission, 54% of family caregivers reported high post-traumatic stress symptom levels, which decreased during the first six months after patient discharge. Lower levels of hope, being younger, having more comorbidities and being on sick leave were associated with higher post-traumatic stress symptom levels. Being the parent of the patient was associated with decreased post-traumatic stress symptom levels. Conclusions Family caregivers of intensive care unit patients report high levels of post-traumatic stress symptoms. Higher levels of hope were associated with fewer post-traumatic stress symptoms.