PURPOSE: Major trauma is a leading cause of acute morbidity and mortality. While injury severity drives much of the associated burden, pre-existing comorbidities may influence both acute management and long-term outcomes. This scoping review examines the impact of comorbidities on trauma outcomes. METHODS: Embase, Medline, CINAHL, Cochrane Library, and PubMed were systematically searched from inception to 22/04/2021 (update 22/03/2024). Studies investigating comorbidities as risk factors for adverse outcomes in adults (≥ 18 years) with major trauma were included. RESULTS: Of 5448 studies identified, 33 met inclusion criteria. No studies examined whether comorbidities increases the risk of major trauma, and only two studies investigated the development of comorbidities post-trauma. Among trauma patients with pre-existing comorbidities particularly cardiovascular disease, diabetes, liver disease, and kidney disease were associated with higher case fatality. Comorbidities were also associated with increased morbidity, longer hospital stays and higher complication rates. CONCLUSIONS: Trauma patients with comorbidities suffer experience worse outcomes, yet limited research explores whether comorbidities contribute to trauma risk or emerge as a consequence. Further research is needed to clarify these relationships and guide targeted interventions.