Aims Describe injury profile and costs of older people trauma in New South Wales; quantify variations with peer group costs; identify predictors of higher costs. Methods Nine level 1 New South Wales trauma centres provided data on major traumas (aged ≥55 years) during 2008–2009 financial year. Trauma register and financial data of each institution were linked. Treatment costs were compared with peer group Australian Refined Diagnostic Related Groups costs, on which hospital funding is based. Variables examined through multivariate analyses. Results Six thousand two hundred and eighty‐nine patients were admitted for trauma. Most common injury mechanism was falls (74.8%) then road trauma (14.9%). Median patient cost was $7044 (Q1‐3: $3405–13 930) and total treatment costs $76 694 252. Treatment costs were $5 813 975 above peer group average. Intensive care unit admission, age, injury severity score, length of stay and traumatic brain injury were independent predictors of increased costs. Conclusion Older people trauma attracts greater costs and length of stay. Cost increases with age and injury severity. Hospital financial information and trauma registry data provides accurate cost information that may inform future funding.