Purpose: To calculate and analyze the effective radiation doses from computed tomography (CT) and radiologic intervention in patients with trauma critical pathway (CP) activation in emergency department (ED), and further, to estimate the lifetime attributable risk (LAR) of incidence and mortality of cancers by the radiation dose. Methods: Through the retrospective electrical chart review of 104 injured patients who trauma critical pathway were activated from November 2012 to March 2013, we calculated radiologic effective doses, which are to multiply Dose-Linear Product of the scan by conversion coefficient. After determination of the image results whether negative or positive, we calculated the effective dose for each group. With these results, we estimated the LAR of incidence and mortality of cancers using Biologic Effects of Ionizing Radiation (BEIR)- VII report table. Results: Total 76 patients were enrolled. The mean age was 49.0±8.5years. The mean injury severity score (ISS) was 12.7±8.4. The cumulative effective dose (CED) for individual patient varied from 2.8 mSv to 238.8mSv, and the mean was 47.6±39.9 mSv. The CED in patients whose ISS≥16 (63.2±26.6 mSv) was higher than that of patients whose ISS<16 (33.5±23.1 mSv) (p<0.001). The CED in patients who were treated with operation or intervention (69.0±45.2 mSv) was higher than that of patients who were treated conservatively (33.6±22.4 mSv) (p<0.001). The LARs of cancer incidence and mortality were 328.5±308.6 and 189.0±159.3 per 100,000 people, respectively. Conclusion: The CED and LAR for trauma CP-activated patients in the ED were significant and we might try to decrease the effective dose exposed to severely injured patients.