This study aims to determine the incremental cost of TBI during the first year after a traffic accident, compared to other patients with similar non-TBI injuries. Secondly, identification of factors associated with medical costs of TBI is pursued. Analyses were performed on administrative data for traffic victims hospitalised in Belgium between 2009 and 2011. Medical costs attributable to the accident are estimated over one year post-injury. Cases with TBI were matched to controls with similar non-TBI injuries to determine the incremental cost of TBI. Both aims of this research were assessed using regression analysis. The incremental cost of TBI is estimated to range between € 10 042 (95%CI [€8198; €11 887]) and €21 715 (95%CI [€13 5889; €29 540]). Age, problems with self-reliance, survival status, the occurrence of acute events and severity of TBI are significant predictors of medical costs. As to healthcare utilisation, MRI usage, inpatient rehabilitation facilities, nursing homes and readmissions to acute hospital stand out as having most influence on costs. This study reveals a considerable incremental cost of TBI. Policy-making bodies should be made aware of this phenomenon and a diversified policy should be considered when financing programs are discussed.