Total-body CT (TBCT) scanning in trauma patients is being increasingly used in trauma assessment. One of the major disadvantages of CT scanning is the amount of radiation exposure involved. The aim of this study was to assess the number of radiological investigations and their associated radiation exposure in multitrauma patients before and after the introduction of a total-body CT protocol as a primary diagnostic tool. The Trauma Registry was used to identify trauma patients admitted to our Level 1 trauma centre in 2008 (pre-TBCT protocol) and 2010 (post-TBCT protocol). Consecutive patients with an Injury Severity Score of ≥16 were included. Patients aged 16 or under, referrals from other hospitals and patients with specific low-energy injury mechanisms were excluded. Subsequent effective doses were estimated from literature and from dose calculations. Three hundred one patients were included, 150 patients pre- and 151 post-introduction of the TBCT protocol. Demographics were comparable. In 2008, 20 % of severely injured patients underwent total-body CT scan, compared with 46 % of the patients in 2010. Trauma room radiation doses for conventional radiographs were significantly higher in 2008, while doses for CT scans were significantly lower. The total effective dose of trauma room radiological investigations was 16 milliSieverts (mSv) in 2008 vs. 24 mSv in 2010 (P = 0.223). The overall effective dose during the total hospital admission was not significantly different between 2008 and 2010 (20 vs. 24 mSv, P = 0.509).In conlusion, after the introduction of a dedicated TBCT protocol, the TBCT rate was more than doubled. Although this increased the CT-induced trauma room radiation dose, the overall radiation dose throughout hospital admission was comparable between patients in 2008 and 2010.