A recent US cohort study estimated 500 cancer cases attributable to exposure to CT out of 600,000 children aged <15 years who underwent a computed tomography (CT) to head or abdomen. This review synthetizes the evidence on the association between exposure to ionizing radiation through CT and cancer risk. Five cohort studies were identified. Three studies show clear increases in cancer risk among children and adolescents who underwent at least one CT. All studies had methodological limits, among which the lack of an individual level estimate of dose-organ specific absorbed by patient and problems of statistical power. Results from on-going large international studies will allow a more accurate risk estimation.