Background: Paediatric Traumatic Brain Injury (TBI) has received less research attention compared to TBI in adults, despite its potential morbidity in all ages. Our aim was to determine whether neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and glucose levels at admission can reliably predict the need for imaging in children presenting with mild TBI. Methods: We retrospectively reviewed the clinical records of paediatric patients who presented in the emergency department with mild TBI within a 5 year period and had undergone computed tomography (CT) scan of the head. Results: Overall, 43 eligible patients were included in the study, with falls being the most commonly reported cause of injury. Twenty-three children had positive CT findings. Patients with abnormal CT findings were found to have higher NLR ratios compated with patients with normal CT, with the mean NLR on admission being 5.2 \pm 3.8. Children with abnormal CT findings had lower PLR levels and higher glucose levels at presentation compared to children with normal CT, however the differences were not statistically significant. Using the receiver operating characteristic (ROC) curve, we found that a NLR cut off value of 6.1 yielded a sensitivity of 54.2% and a specificity of 89.5% for the prediction of abnormal CT findings. Conclusions: The findings of this study suggest that NLR may have a role in CT decision-making in the emergency department for mild TBI in paediatric patients.