Objective: Various parameters are used to differentiate between complicated and uncomplicated appendicitis cases, and scoring systems are even created where these parameters are used together. The aim of this study was to evaluate the effectiveness of one of these scoring systems by external validation. Methodology: Retrospective evaluation was performed on the clinical, radiological and laboratory findings of patients who underwent an appendectomy between January 2018 and January 2021. Scoring was performed using the previously described scoring systems for each patient considered to have acute appendicitis as a result of imaging. They were divided into complicated appendicitis and uncomplicated appendicitis groups, according to clinical and pathological evaluation results. Results: While evaluating 425 patients, ultrasonography was used in 48% and tomography in 52% of the patients. Significant effectiveness of the score of ≤6 was observed in the group using tomography (p<0.001, AUC: 0.838, Sensitivity 83.3%, positive predictive value 50.8%, specificity 84.3%, negative predictive value 96.3%). Significant effectiveness of the score of ≤5 was observed in the ultrasonography group (p<0.001, AUC: 0.790, Sensitivity 85.7%, positive predictive value 39.0%, specificity 72.2%, negative predictive value 96.1%). Conclusion: The scoring system created for the selection of uncomplicated appendicitis cases has been shown to be effective and has been externally validated. Since each of the parameters used in the scoring system has higher efficiency than its independent effectiveness, scoring systems that evaluate clinical, radiological and laboratory variables together, give better results in clinical practice.