简介：AbstractPurpose:The reliability of trauma coding is essential in establishing the reliable trauma data and adopting efficient control and monitoring policies. The present study aimed to determine the reliability of trauma coding in educational hospitals affiliated to Shahid Beheshti University of Medical Sciences, Iran.Methods:In this descriptive cross-sectional study, 591 coded medical records with a trauma diagnosis in 2018 were selected and recoded by two coders. The reliability of trauma coding was calculated using Cohen's kappa. The data were recorded in a checklist, in which the validity of the content had been confirmed by experts.Results:The reliability of the coding related to the nature of trauma in research units was 0.75—0.77, indicating moderate reliability. Also, the reliability of the coding of external causes of trauma was 0.57—0.58, suggesting poor reliability.Conclusion:The reliability of trauma coding both in terms of the nature of trauma and the external causes of trauma does not have a good status in the research units. This can be due to the complex coding of trauma, poor documentation of the cases, and not studying the entire case. Therefore, holding training courses for coders, offering training on the accurate documentation to other service providers, and periodically auditing the medical coding are recommended.