Objective: In this study, we aimed to show the effectiveness of Alvarado score and its components to predict the correct diagnosis of acute appendicitis and to find an optimum cut-off value for Alvarado score. Material and Methods: The patients who underwent surgical operation between January 2011 and January 2012 with the suspicion of acute appendicitis were included in the study. Their demographic and clinical features and histopathological results were retrieved from the medical records. They were divided into three groups according to their Alvarado scores. With the use of "receiver operating characteristic" curve analysis, the optimum cut-off value needed to make a correct diagnosis of acute appendicitis was determined. Results: In all, 156 patients were included into the study. The mean age was 31.41±13.27 years. Histopathologically, acute appendicitis was detected in 125 (80.1%) patients, and negative appendectomy was found in 31 patients (19.8%). Mean Alvarado score was 6.44±1.49. There was a significant correlation between negative appendectomy and low Alvarado score (p<0.001). The main component of Alvarado score that makes the difference was rebound. Fever higher than 37.3°C, rebound, loss of appetite, and existence of shifting pain were statistically differential components (p=0.042, p<0.001, p=0.045, p<0.001, respectively). The rate of correct diagnosis of acute appendicitis was maximum in group 3 (100%) and minimum in group 1 (21.7%). Optimum cut-off value for Alvarado score was 7.Conclusion: Patients with an Alvarado score of over 7 can be taken into surgical operation without the need of imaging methods.