Aim: This study aims to determine the incremental cost of having a TBI in older adults, as well as the incremental cost of being of older age in patients with TBI. Method: Incremental costs were assessed for both hospital and the period of one year post-injury. Data on patients aged 65 years and older with TBI were retrieved from a database of all transport-related trauma admissions in Belgium between 2009 and 2011. Each case was matched to two similar controls who were (1) older without TBI or (2) younger with TBI. Incremental costs were estimated by comparing cases with controls using both simple and multiple regression. Results: The incremental cost of TBI at older age was most pronounced for those with skull fracture and intracranial injury (hospital: increase with multiplicative factor of 1.39, 95%CI [1.14;1.69]; one-year: 1.45, 95%CI [1.17;1.80]). The incremental cost of being of older age was highest for patients older than 75 years (hospital: 1.27, 95%CI [1.09;1.47]; one-year: 1.74, 95%CI [1.47;2.05]). Conclusion: The incremental costs estimated in this study are valuable for further health economic research and policymaking in response to the changing demographics of traffic participants.