Background: A medication error is defined as any inappropriate drug administration that can harm the patient while being preventable and equally occurring under the supervision of a medical team. Objectives: The current study was conducted to clarify the error status, evaluate the regularity of medical mistakes in a referral hospital in the South West of Iran. Methods: Data were gathered from multiple wards at various shift works based on an optional error reporting form, either self-reporting or colleague-reporting, and then it has been made available to the "Quality Improvement Office" experts. Since the current study was retrospective, the samples were calculated from 2017 to 2019. The average and standard deviations were implemented to describe qualitative variables, and ANOVA to determine any statistically significant differences between groups. Results: Of 305 medication errors reported to the Quality Improvement Office, the "Administering the wrong drug" rate was 32.5%, and it has dedicated the most significant percentage of mistake types. The most-reported medication errors occurred in the general ward, and there was no significant difference in the number of mistakes in other shifts. Conclusion: Results suggest there is an association between the incidence of medication errors and the therapeutic ward. Although the most prevalent medication error in this study was "Administering the wrong drug. Keywords: medical error, error reporting, drug administration, mistakes, hospital